Multilayer structure including insulating adhesive layer and cured product thereof

Abstract

Provided are: a multilayer structure including an insulating adhesive layer that exhibits a low dielectric constant, a low dielectric loss tangent, and a low water absorption rate, and that exhibits high adhesion to a metal foil, an insulating resin layer, or both by curing; and a cured product, etc. A multilayer structure according to the present invention is characterized by comprising: a metal foil having an open surface in at least a portion thereof; an insulating resin layer; and an insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxylic acid group or an acid anhydride group, the insulating adhesive layer being bonded to the insulating resin layer. And the insulating adhesive layer is bonded to the surface of the metal foil on the opposite side from the open surface.

Description

Technical Field

[0001] The present invention relates to a multilayer structure having both a metal foil and an insulating resin layer, or having an insulating adhesive layer formed from a composition having high adhesiveness on a metal foil or an insulating resin layer, a cured product thereof, and the like. Background Art

[0002] As communication frequencies develop toward high-frequency bands of gigahertz bands and above gigahertz bands, the demand for multilayer substrates, transmission lines, and antennas formed from CCLs and FCCLs containing insulating materials having low dielectric properties has increased. Fluorine-based resins such as perfluoroethylene have excellent characteristics of low dielectric constant, low dielectric loss, and excellent heat resistance, but are difficult in terms of molding processability and film formability, and there are also problems in terms of adhesiveness to copper foil for wiring, and thus it is difficult to apply them to multilayer substrates and the like. On the other hand, substrates and insulating materials using post-curing resins such as epoxy resins, unsaturated polyester resins, polyimide resins, and phenolic resins are widely used because of their heat resistance and ease of operation, but have high dielectric constants and dielectric losses, and improvement is desired as insulating materials for high frequencies (Patent Document 1).

[0003] Therefore, hydrocarbon resins having low dielectric properties inherently have attracted attention. Originally, in order to make a hydrocarbon resin, which is a thermoplastic resin, into a curable resin, it is necessary to introduce a functional group. However, generally, functional groups that undergo crosslinking reactions by radicals or heat have polarity, and thus when these functional groups are introduced into a hydrocarbon resin, the dielectric properties deteriorate. When introducing a functional group composed only of hydrocarbons such as aromatic vinyl, in many cases, intermolecular reactions between expensive hydrocarbon monomers are used (Patent Document 2), and it is not economical in many cases. Patent Document 3 shows a cured product formed from an ethylene-olefin (aromatic vinyl compound)-aromatic polyene copolymer and a nonpolar vinyl compound copolymer having a specific composition and coordination obtained from a specific coordination polymerization catalyst. In the case of this technology, only one of the two vinyl groups of aromatic polyene (divinylbenzene) is selectively copolymerized and the remaining vinyl group is retained, and thus a hydrocarbon copolymer macromonomer having a functional group of aromatic vinyl can be easily obtained. Cured products obtained from the same olefin-aromatic vinyl compound-aromatic polyene copolymer and a composition such as a co-reactant have characteristics such as low dielectric constant and low dielectric loss tangent, and wide-ranging physical properties from soft to hard can be imparted by selecting the composition and appropriate co-reactants (Patent Documents 4 and 5). In addition, as shown in the examples, these materials can exhibit high adhesiveness (adhesive strength) to the roughened surface of copper foil.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 6-192392

[0007] Patent Document 2: Japanese Patent Laid-Open No. 2004-087639

[0008] Patent Document 3: Japanese Patent Laid-Open No. 2007-217706

[0009] Patent Document 4: International Publication No. 2021 / 112087

[0010] Patent Document 5: International Publication No. 2021 / 112088 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] However, especially when applied to high-frequency signal transmission lines such as microstrip lines, antennas, and various substrate materials and insulating materials for high-frequency signals such as interlayer insulating materials for multilayer substrates, not only a high adhesive force to metal foils such as copper foil is required, but also a high adhesive force to various substrate materials is required.

[0013] Regarding the problems of exhibiting low dielectric constant and dielectric loss tangent, low water absorption rate, showing adhesiveness to metal foil and insulating resin layer through curing, and also having a high adhesive force to metal foil or insulating resin layer or both, these have not been fully considered in the prior art.

[0014] Means for Solving the Problems

[0015] The inventors of the present application conducted in-depth research to solve the above problems and found that by using an insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxyl group or an acid anhydride group, the above problems can be solved, thus completing the present invention. That is, the present invention provides the following specific embodiments.

[0016] Embodiment 1.

[0017] A multilayer structure, characterized by comprising: a metal foil having an open surface in at least a part;

[0018] an insulating resin layer; and

[0019] an insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxyl group or an acid anhydride group,

[0020] the aforementioned insulating adhesive layer is joined to the aforementioned insulating resin layer, and the aforementioned insulating adhesive layer is joined to the surface of the aforementioned metal foil opposite to the aforementioned open surface.

[0021] Embodiment 2.

[0022] The multilayer structure according to Mode 1, wherein the open surface of the metal foil is the entire surface area of the metal foil.

[0023] Mode 3.

[0024] The multilayer structure according to Mode 1, wherein the open surface of the metal foil is a part of the surface area of the metal foil, and a covering film is also provided on other parts other than this part.

[0025] Mode 4.

[0026] The multilayer structure according to any one of Modes 1 to 3, wherein the open surface of the metal foil is provided for mounting components.

[0027] Mode 5.

[0028] The multilayer structure according to any one of Modes 1 to 4, which has any one of the following structures (1) or (2):

[0029] Structure (1): A structure joined in the order of the metal foil, the insulating adhesive layer, and the insulating resin layer;

[0030] Structure (2): A structure joined in the order of the metal foil, the insulating adhesive layer, the insulating resin layer, the insulating adhesive layer, and the metal foil.

[0031] Mode 6.

[0032] The multilayer structure according to Mode 5, wherein in the aforementioned structure (1) or structure (2), the areas of the aforementioned layers are the same.

[0033] Mode 7.

[0034] The multilayer structure according to Mode 5, wherein in the aforementioned structure (1) or structure (2), the areas of at least a pair of the aforementioned layers are different.

[0035] Mode 8.

[0036] The multilayer structure according to any one of Modes 1 to 7, wherein the insulating resin layer contains one or more selected from the group consisting of polyimide (PI), liquid crystal polymer (LCP), polyphenylene ether (PPE), polyfunctional aromatic vinyl resin (ODV), and epoxy resin.

[0037] Mode 9.

[0038] The multilayer structure according to any one of Modes 1 to 8, wherein the olefin-aromatic vinyl compound-aromatic polyene copolymer contained in the insulating adhesive layer satisfies all of the following conditions (1) to (4).

[0039] (1) The number-average molecular weight of the copolymer is 500 or more and less than 100,000;

[0040] (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer unit is 0 to 98% by mass or less;

[0041] (3) The aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms having a plurality of vinyl groups and / or vinylidene groups in the molecule, and the content of vinyl groups and / or vinylidene groups derived from the aromatic polyene unit is 2 or more and less than 20 relative to the number-average molecular weight;

[0042] (4) The olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, the content of the olefin monomer unit is 1% by mass or more, and the total of the olefin monomer unit, the aromatic vinyl compound monomer unit, and the aromatic polyene monomer unit is 100% by mass.

[0043] Mode 10.

[0044] The multilayer structure according to any one of Modes 1 to 9, wherein the content of the monomer or polymer having a carboxyl group or an acid anhydride group contained in the insulating adhesive layer is 0.001 to 5 parts by mass with respect to 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer.

[0045] Mode 11.

[0046] A cured product of a multilayer structure, which is obtained by curing the multilayer structure according to any one of Modes 1 to 10.

[0047] Mode 12.

[0048] A signal transmission line for high frequencies, an antenna, and a multilayer FCCL including the cured product of the multilayer structure described in Mode 11.

[0049] Mode 13.

[0050] RCC (resin-coated copper foil), characterized by comprising:

[0051] a metal foil having an open surface in at least a part; and

[0052] An insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxyl group or an acid anhydride group.

[0053] The aforementioned insulating adhesive layer is joined to the surface on the opposite side of the aforementioned open surface of the aforementioned metal foil.

[0054] Method 14.

[0055] A multilayer sheet containing an insulating adhesive layer and an insulating resin layer. The aforementioned insulating adhesive layer is formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxyl group or an acid anhydride group. The aforementioned insulating resin layer contains one or more selected from the group consisting of polyimide (PI), liquid crystal polymer (LCP), polyphenylene ether (PPE), polyfunctional aromatic vinyl resin (ODV), and epoxy resin.

[0056] Method 15.

[0057] RCC (Resin Coated Copper Foil), characterized by comprising: a metal foil having an open surface on at least a part; a cured insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer; and an insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer.

[0058] The aforementioned insulating adhesive layer is joined to the surface on the opposite side of the aforementioned open surface of the aforementioned metal foil in the order of the aforementioned metal foil / the aforementioned cured insulating adhesive layer / the aforementioned insulating adhesive layer.

[0059] Method 16.

[0060] The RCC (Resin Coated Copper Foil) according to Method 15, wherein the composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer is a composition containing the aforementioned olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxyl group or an acid anhydride group.

[0061] Advantages of the Invention

[0062] According to the present invention, it is possible to provide an insulating adhesive layer that exhibits a low dielectric constant, a low dielectric loss tangent, and a low water absorption rate, and can be bonded to both a metal foil and an insulating resin layer, or to a metal foil or an insulating resin layer, with a high bonding strength (peel strength). In addition, by including this insulating adhesive layer, it is also possible to provide a multilayer structure useful for high-frequency signal transmission. Description of the Drawings

[0063] Figure 1A ​Shows the structure (1) which is an example of the structure that can be included in part or in whole of the multi-layer structure according to an aspect of the present invention, and its modified examples.

[0064] Figure 1B Shows the structure (2) which is an example of the structure that can be included in part or in whole of the multi-layer structure according to an aspect of the present invention, and its modified examples.

[0065] Figure 2 Shows an example of the manufacturing method of the structure (1).

[0066] Figure 3 Shows another example of the manufacturing method of the structure (1).

[0067] Figure 4 Shows an example of the manufacturing method of the structure (2).

[0068] Figure 5 Shows another example of the manufacturing method of the structure (2). Detailed Description of the Invention

[0069] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. In addition, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings. However, the following embodiments are illustrative of the present invention, and the present invention is not limited thereto. That is, the present invention can be arbitrarily modified and implemented without departing from its gist. It should be noted that, in this specification, for example, the expression of the numerical range of "1 to 100" includes both its lower limit value "1" and upper limit value "100". The same applies to the expressions of other numerical ranges.

[0070] The multi-layer structure of the present embodiment includes a metal foil having an open surface and an insulating adhesive layer bonded to the metal foil, and preferably further includes an insulating resin layer bonded to the insulating adhesive layer. It should be noted that, in this specification, having an "open surface" means that at least a part (or all) of one side of a certain layer (such as a metal foil) is not bonded to other layers.

[0071] ​​​​​The open surface of the metal foil is typically provided on an intermediate product (a product that is scheduled to become part of another product in the future). That is, it can be considered that at least a portion of the open surface of the metal foil is a location where components (LSI, transistors, diodes, etc.) are scheduled to be mounted in the future. Therefore, the open surface is sometimes accompanied by a protective material (protective film, release paper, etc.) to avoid damage or contamination. However, sometimes such a protective material is easy to remove during use, and it is still an open surface when used industrially. That is, in this specification, the surface with such a protective material is also defined as an "open surface". In other words, the definition of the multilayer structure in this specification does not take into account the presence or absence of such a protective material. That is, a protective material that is scheduled to be easily removed when used in industry is not considered to be a part of the present multilayer structure.

[0072] The open surface of the metal foil may occupy the entire surface area of ​​the metal foil, or may occupy a portion of the surface area (preferably 50% or more, 70% or more, or 80% or more of the area). When the open surface of the metal foil is a portion of the surface area of ​​the metal foil, it may be in a form where other layers (e.g., a cover film) are present in other portions other than the portion.

[0073] An example of the basic structure of the multilayer structure is shown in Figure 1A and Figure 1B That is, the insulating adhesive layer is preferably bonded to both the metal foil and the insulating resin layer. The multilayer structure may further include other layers.

[0074] Figure 1A The structure (1) shown is a structure formed by joining a metal foil, an insulating adhesive layer, and an insulating resin layer in the order from the top of the figure. For the metal foil, the upper surface is an open surface, and the lower surface is joined to the insulating adhesive layer. In addition, a modified example of the structure (1) is a structure in which the area of ​​the metal foil is smaller than that of the other layers. It should be noted that the "upper", "lower", "outer" and "inner" in the description here are for the sake of convenience and do not determine the upper and lower sides of the actual product.

[0075] Figure 1B The structure (2) shown is a structure formed by joining the metal foil, the insulating adhesive layer, the insulating resin layer, the insulating adhesive layer, and the metal foil in the order from the top of the figure. For any metal foil, the outer surface is an open surface, and the inner surface is joined to the insulating adhesive layer. In addition, a modified example of the structure (2) is a structure in which the area of ​​the metal foil of both layers is smaller than that of the other layers. In another embodiment, the area of ​​the metal foil of only one layer may be smaller than that of the other layers.

[0076] In a certain embodiment, like structures (1) and (2), the areas of the respective layers forming the multi-layer structure may be the same. In another embodiment, like the above-described modification example, the areas of at least a pair of the respective layers forming the multi-layer structure may be different.

[0077] The so-called insulating adhesive layer included in the present multi-layer structure includes the concepts of high-frequency signal transmission lines such as FCCL and microstrip lines, interlayer adhesive materials, bonding sheets, and the resin layer of RCC (Resin Coated Copper). The concept of a sheet also includes the concept of a film. In addition, in this specification, even if it is described as a film, it also includes the concept of a sheet. Hereinafter, the composition according to the present embodiment will be described in more detail. In this specification, the so-called composition includes the concept of varnish. That is, the composition in a liquid state in the composition is described as varnish.

[0078] In a certain embodiment, it is also possible to provide RCC (Resin Coated Copper) which includes a metal foil having an open surface in at least a part and an insulating adhesive layer, and the insulating adhesive layer is joined to the surface on the opposite side of the open surface of the metal foil. RCC can be considered as one kind or a part of the above multi-layer structure.

[0079] RCC (in which the metal foil can be processed into wiring) can be suitably used in the lamination process. Recently, for example, in order to multiply 5 layers or more, the insulating adhesive layer is also required to be further thinned. In order to ensure the reliability during lamination, it is effective to cure at least one layer of the present insulating adhesive layer in advance (hereinafter referred to as RCC with a cured insulating adhesive layer). The present cured insulating adhesive layer is preferably arranged between the metal foil and the insulating adhesive layer. The thickness of the cured insulating adhesive layer and the insulating adhesive layer of the present RCC with a cured insulating adhesive layer is arbitrary. Generally, the metal foil such as copper foil is preferably 5 to 20 μm, the cured insulating adhesive layer is preferably 5 to 50 μm, and the insulating adhesive layer is preferably 10 to 50 μm. A multilayer structure with an insulating layer including a laminated structure using RCC or the present RCC with a cured insulating adhesive layer is suitable as a constituent element of a laminated substrate. In particular, in the manufacturing process of the laminated substrate, for the present RCC with a cured insulating adhesive layer, since the insulating adhesive layer buries the surface unevenness of the wiring when the RCC is laminated, the cured insulating adhesive layer can ensure insulation, so it is preferably used. In this structure, especially when adhesion to the insulating resin layer is not required, it is not necessary to use a composition of an olefin-aromatic vinyl compound-aromatic polyene copolymer containing a monomer or polymer having a carboxylic acid group or anhydride group. However, in the case where the insulating resin layer of the core substrate of the laminated substrate obtained by the lamination process is a resin specified in this specification, it is preferred to use a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxylic acid group or anhydride group. That is, as another aspect of the present invention, another mode is RCC (resin-coated copper foil), characterized in that it comprises: a metal foil having an open surface at least in part; a cured insulating adhesive layer, which is formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer; and an insulating adhesive layer, which is formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer, and the aforementioned insulating adhesive layer is bonded to the surface on the opposite side of the aforementioned open surface of the aforementioned metal foil in the order of the aforementioned metal foil / the aforementioned cured insulating adhesive layer / the aforementioned insulating adhesive layer. More preferably, in the aforementioned RCC (resin coated copper foil), the composition containing the olefin-aromatic vinyl compound-aromatic polyene copolymer is a composition containing the olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxylic acid group or anhydride group.

[0080] <Metal foil and roughened surface>

[0081] The so-called metal foil (one or more pieces) contained in the present multi-layer structure (in the use of electronic materials, preferably a conductive copper foil, aluminum foil, etc.) can be any metal foil as long as it can be used for industrial purposes such as wiring and substrates. As the metal foil, in addition to copper foil, aluminum foil, stainless steel foil, nickel foil, titanium foil, platinum foil, etc. can be cited, but it is not particularly limited to these. The thickness of the metal foil can be appropriately set according to the desired performance and is not particularly limited, usually in the range of 1 to 500 μm, preferably in the range of 5 to 50 μm. As the metal foil, a copper foil suitable for high frequencies is preferred, and it can be a rolled copper foil or an electrolytic copper foil. The metal foil can have a roughened surface (also known as a matte surface, sometimes expressed as the M surface) and a smooth surface (glossy surface or polished surface, sometimes expressed as the S surface). For example, the surface roughness (maximum height) Rz specified in JIS B0601:2001 of the roughened surface of the metal foil is preferably 5 μm or less, particularly preferably 3 μm or less. For example, the surface roughness (maximum height) Rz specified in JIS B0601:2001 of the roughened surface of the metal foil is preferably greater than 0.5 μm. Metal foils such as copper foils suitable for such conditions can be obtained from Furukawa Electric Co., Ltd., JX Metals Co., Ltd., Mitsui Mining & Smelting Co., Ltd., etc.

[0082] <Smoothing surface of metal foil>

[0083] The so-called smoothing surface of a metal foil such as a copper foil is the surface of the metal foil used for wiring and substrates that is not the roughened surface and is a relatively smooth surface compared to the roughened surface. Generally, the surface roughness (maximum height) Rz specified in JIS B0601:2001 of this smoothing surface is 0.5 μm or less, but as long as it is a relatively smooth surface compared to the roughened surface or a surface with relatively high gloss as described above, there is no particular limitation. Those skilled in the art can easily identify and distinguish the smoothing surface and the roughened surface of a metal foil such as a copper foil. The insulating adhesive layer of the present embodiment can exhibit high adhesiveness to any of the roughened surface and the smoothing surface. The insulating adhesive layer can be bonded to the roughened surface of the metal foil or the smoothing surface, but usually it is bonded to the roughened surface.

[0084] <Insulating resin layer>

[0085] The insulating resin layer included in this multi-layer structure is a layer containing a resin having insulating properties. As the resin having insulating properties, known insulating resins can be used, and there is no particular limitation. Preferred examples include one or more selected from the group consisting of polyimide (PI), liquid crystal polymer (LCP), polyphenylene ether (PPE), polyfunctional aromatic vinyl resin (ODV), and epoxy resin, but it is not particularly limited to these. However, for the insulating resin layer, since it usually does not have adhesion in the case of monomers, in this specification, it does not include the insulating adhesive layer described later. Its thickness is arbitrary, and preferably 10 μm to 1 mm. It should be noted that in this specification, the thickness of the insulating resin layer refers to the average value of 9 randomly selected locations. In addition, from the viewpoints of improving the strength of the structure and reducing the coefficient of linear expansion (CTE), the insulating resin layer preferably contains reinforcing materials such as fillers and glass cloth. In addition, the aforementioned polyimide (PI) is a concept including modified polyimide (MPI) with further reduced dielectric constant, dielectric loss tangent, and water absorption rate. In addition, as the aforementioned polyphenylene ether, curable PPE having a functional group is preferred.

[0086] <Insulating Adhesive Layer>

[0087] The insulating adhesive layer included in this multi-layer structure is a layer formed from a composition having adhesiveness. The thickness of the insulating adhesive layer can be appropriately set according to the desired performance and is arbitrary, usually 1 μm to 500 μm, preferably 5 μm to 100 μm. It should be noted that in this specification, the thickness of the insulating adhesive layer refers to the average value of 9 randomly selected locations. For the composition for forming the insulating layer included in this multi-layer structure, as its main component, an olefin-aromatic vinyl compound-aromatic polyene copolymer is preferably included. Here, the so-called inclusion as the main component of the composition means inclusion in an amount greater than 50% by mass relative to 100 parts by mass of the composition. This composition preferably further includes a monomer or polymer having a carboxyl group or an acid anhydride group. Specifically, relative to 100 parts by mass of this olefin-aromatic vinyl compound-aromatic polyene copolymer, it is more preferably included 0.001 to 5 parts by mass of a monomer or polymer having a carboxyl group or an acid anhydride group, and further preferably included 0.01 to 5 parts by mass of a monomer or polymer having a carboxyl group or an acid anhydride group. For this insulating adhesive layer, at least a part of it is in contact with the metal foil. In the case where there are multiple insulating adhesive layers, it is preferred that at least one surface of all the insulating adhesive layers has contact with the metal foil (in other words, in the case of having multiple insulating adhesive layers, at least one surface of each insulating adhesive layer has contact with the metal foil). In a certain embodiment, it is preferred that the insulating adhesive layer is in contact with the smooth surface of the metal foil, and / or it is preferred that any surface of the insulating adhesive layer is not adhered to the roughened surface of the metal foil. In a certain embodiment, in the insulating adhesive layer, relative to the whole composition, it can include 30% by mass or more of the olefin-aromatic vinyl compound-aromatic polyene copolymer, and it can include preferably 50% by mass or more, more preferably 70% by mass or more of the olefin-aromatic vinyl compound-aromatic polyene copolymer. This olefin-aromatic vinyl compound-aromatic polyene copolymer can be obtained by copolymerizing each monomer of an olefin, an aromatic vinyl compound, and an aromatic polyene. The insulating adhesive layer can be in an uncured or semi-cured state. The uncured or semi-cured insulating adhesive layer can be processed under appropriate conditions to form a fully cured body after being laminated with other layers of this multi-layer structure, such as a metal foil like a copper foil, and an insulating resin layer.

[0088] The so-called olefin monomer is one or more selected from α-olefins having 2 to 20 carbon atoms and cyclic olefins having 5 to 20 carbon atoms, and is a compound composed of carbon and hydrogen substantially without oxygen, nitrogen, and halogen. As α-olefins having 2 to 20 carbon atoms, for example, ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decane, 1-dodecane, 4-methyl-1-pentene, 3,5,5-trimethyl-1-hexene can be exemplified, but not particularly limited to these. As cyclic olefins having 5 to 20 carbon atoms, norbornene, cyclopentene can be exemplified, but not particularly limited to these. Substances preferably used as olefins include combinations of ethylene and other α-olefins or cyclic olefins other than ethylene, or ethylene alone, but not particularly limited to these. In addition, in the preferred combination of ethylene and other α-olefins other than ethylene, the glass transition temperature of the ethylene-α-olefin-aromatic vinyl compound-aromatic polyene copolymer of the finally obtained cured product can be freely adjusted within the range of about -60°C to -10°C by the type and content of the α-olefin.

[0089] The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 to 20 carbon atoms. As the aromatic vinyl compound monomer, for example, styrene, p-methylstyrene, p-isobutylstyrene, various vinylnaphthalenes, various vinylanthracenes can be exemplified, but not particularly limited to these.

[0090] As the aromatic polyene monomer, it is a polyene having 5 to 20 carbon atoms with multiple vinyl groups and / or vinylene groups in its molecule. As the aromatic polyene monomer, preferably, various divinylbenzenes in the ortho, meta, and para positions or mixtures thereof, divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, p-3-butenylstyrene, etc., which have an aromatic vinyl structure and are substantially composed of carbon and hydrogen without oxygen, nitrogen, and halogen, can be exemplified, but not particularly limited to these. In addition, the bifunctional aromatic vinyl compound described in JP-A-2004-087639, for example, 1,2-bis(vinylphenyl)ethane (abbreviation: BVPE), can also be used as the aromatic polyene monomer. Among them, it is preferred to use various divinylbenzenes in the ortho, meta, and para positions or mixtures thereof, and most preferably to use a mixture of m-divinylbenzene and p-divinylbenzene. In this specification, these divinylbenzenes are referred to as divinylbenzene-based. When using divinylbenzene-based as the aromatic polyene, the curing efficiency is high during the curing treatment and it is easy to cure.

[0091] As each of the above-mentioned olefins, aromatic vinyl compounds, and aromatic polyenes, other olefins containing polar groups such as oxygen atoms and nitrogen atoms, aromatic vinyl compounds containing oxygen atoms, nitrogen atoms, etc., or aromatic polyenes containing oxygen atoms, nitrogen atoms, etc. may also be included. The total mass of these monomers containing polar groups can be appropriately set according to the desired properties and is not particularly limited. It is preferably 10% by mass or less, more preferably 3% by mass or less, and most preferably does not contain monomers containing polar groups of the total mass of this composition. By setting it to 10% by mass or less, the dielectric properties (low dielectric constant, low dielectric loss) of the cured product obtained by curing this composition can be improved.

[0092] This olefin-aromatic vinyl compound-aromatic polyene copolymer preferably satisfies all of the following conditions (1) to (4).

[0093] (1) The number average molecular weight of the copolymer is 500 or more and less than 100,000.

[0094] (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer unit is 0 to 98% by mass or less.

[0095] (3) The aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene unit is 2 or more and less than 20 relative to the number average molecular weight.

[0096] (4) The olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, the content of the olefin monomer unit is 1% by mass or more, and the total of the olefin monomer unit, the aromatic vinyl compound monomer unit, and the aromatic polyene monomer unit is 100% by mass.

[0097] The number average molecular weight (Mn) of the copolymer can be 500 or more and less than 100,000. In this specification, the so-called number average molecular weight being 500 or more and less than 100,000 means that the molecular weight converted to standard polystyrene obtained by the GPC (gel permeation chromatography; gel permeation chromatography) method falls within this range.

[0098] The content of the aromatic vinyl compound monomer unit contained in the copolymer may be 0% by mass or more and 98% by mass or less, and is more preferably 10% by mass or more and 70% by mass or less. When the content of the aromatic vinyl compound monomer unit is 70% by mass or less, the glass transition temperature of the cured product of the finally obtained composition becomes lower than the temperature near room temperature, and there is a tendency to further improve the toughness and elongation at low temperature, so it is preferred. If the content of the aromatic vinyl compound monomer unit is 10% by mass or more, there is a tendency to easily obtain the following effects: the aromaticity of the copolymer is improved, the affinity with the flame retardant and the filler becomes good, the bleeding of the flame retardant can be avoided, and the filling property of the filler can be improved. In addition, if the content of the aromatic vinyl compound monomer unit is 10% by mass or more, there is a tendency to easily obtain a cured product of a composition having a high adhesive strength with a copper foil and a copper wiring.

[0099] In the copolymer, the content of vinyl and / or vinylene from the aromatic polyene unit, preferably the content of vinyl, may be 2 or more and less than 30, more preferably less than 20, relative to the number average molecular weight, and may be preferably 3 or more and less than 20. If the content of the vinyl and / or vinylene is 2 or more, there is a tendency to easily obtain a cured product with high crosslinking efficiency and sufficient crosslinking density. The content of vinyl from the aromatic polyene unit (divinylbenzene unit) relative to the number average molecular weight in the copolymer can be obtained, for example, by comparing the number average molecular weight (Mn) in terms of standard polystyrene obtained by the GPC (gel permeation chromatography) method known to those skilled in the art, and 1 1H-NMR measurement and / or 13 13C-NMR measurement and the composition and the content of vinyl from the aromatic polyene unit. Such a method is obvious and known to those skilled in the art. In addition, it may also be a certain method described in the patent documents of the prior art documents of this specification.

[0100] In the copolymer, the content of the preferred olefin monomer unit is 1% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and most preferably 30% by mass or more. The total of the aforementioned olefin monomer unit, aromatic vinyl compound monomer unit, and aromatic polyene monomer unit is 100% by mass. If the content of the olefin monomer unit is 1% by mass or more, there is a tendency that the toughness (elongation) and impact resistance of the finally obtained cured product are improved, and breakage during curing and breakage of the cured product in the thermal cycle test are less likely to occur. In the copolymer, the content of the preferred olefin monomer unit is 90% by mass or less.

[0101] For the purpose of obtaining desired physical properties, the copolymer may be a mixture of various copolymers. In the present copolymer, as an olefin-aromatic polyene copolymer that does not contain an aromatic vinyl compound monomer unit, specifically, ethylene-divinylbenzene copolymer, ethylene-propylene-divinylbenzene copolymer, ethylene-1-butene-divinylbenzene copolymer, ethylene-1-hexene-divinylbenzene copolymer, and ethylene-1-octene-divinylbenzene copolymer can be exemplified as preferred examples.

[0102] In the present copolymer, as an olefin-aromatic vinyl compound-aromatic polyene copolymer that contains an aromatic vinyl compound monomer unit, ethylene-styrene-divinylbenzene copolymer, ethylene-propylene-styrene-divinylbenzene copolymer, ethylene-1-hexene-styrene-divinylbenzene copolymer, and ethylene-1-octene-styrene-divinylbenzene copolymer can be exemplified.

[0103] <Monomer or polymer having a carboxyl group or an acid anhydride group>

[0104] The insulating adhesive layer of the present embodiment contains a monomer or a polymer having a carboxyl group or an acid anhydride group. As the monomer having a carboxyl group or an acid anhydride group, monomers known in the art can be used, and there is no particular limitation. Examples include maleic acid, maleic anhydride, phthalic acid, phthalic anhydride, etc. Among these, maleic anhydride is most preferred. As the polymer having a carboxyl group or an acid anhydride group, styrene-maleic anhydride copolymer, styrene-maleic acid copolymer, styrene-phenylmaleimide-maleic anhydride copolymer, and styrene-acrylonitrile-maleic anhydride copolymer can be exemplified, but are not particularly limited to these. The molecular weight of the present polymer is arbitrary. Considering the molding processability of the composition, a lower molecular weight is preferred. Specifically, the weight average molecular weight (Mw) is in the range of 500 to 50,000, and more preferably in the range of 500 to 30,000. The number of monomer units having a carboxyl group or an acid anhydride group in the present polymer can be appropriately set according to the desired properties, and there is no particular limitation. Preferably, it is 2 or more and 20 or less relative to the number average molecular weight. If the number of monomer units is 2 or more, the crosslinking density increases, and if it is 20 or less, the molding processability of the composition tends to improve.

[0105] By using a monomer or polymer having a carboxylic acid group or an acid anhydride group, the insulating adhesive layer can exhibit a high adhesive force to the metal foil and / or various insulating resin layers. The content ratio of the monomer used in the composition of the present embodiment can be appropriately set according to the desired performance and is not particularly limited. With respect to 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer, it is preferably 0.001 to 5 parts by mass, more preferably 0.1 to 3 parts by mass. The content ratio of the polymer used in the composition of the present embodiment can be appropriately set according to the desired performance and is not particularly limited. With respect to 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer, it is preferably 0.001 to 5 parts by mass or 1 to 30 parts by mass, more preferably 1 to 10 parts by mass. By using the amounts within these preferred numerical ranges, the effect that the dielectric constant and the dielectric loss tangent of the obtained cured product do not become too high can be obtained. For example, the dielectric constant can be suppressed to 3.5 or less, preferably 3.0 or less, and the dielectric loss tangent can be suppressed to 0.002 or less, preferably 0.001 or less.

[0106] As other adhesion improvers that can be included in the insulating adhesive layer of the present embodiment, surface modifiers can be cited.

[0107] <Surface modifier>

[0108] The insulating adhesive layer of the present embodiment may contain a surface modifier for the purpose of improving the adhesion to the metal foil and the insulating resin layer, and in particular, can improve the adhesion strength (peel strength) to the smooth surface of the metal foil. The content ratio of the surface modifier can be appropriately set according to the desired performance and is not particularly limited. With respect to 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer, the amount of the surface modifier used is preferably in the range of 0.001 to 10 parts by mass, more preferably in the range of 0.01 to 5 parts by mass, and most preferably in the range of 0.01 to 1 part by mass. If the amount of the surface modifier used is 10 parts by mass or less, the dielectric constant and the dielectric loss tangent of the cured product of the insulating adhesive layer tend to be easily lowered, which is therefore preferred.

[0109] In this embodiment, known surface modifiers can be used. Examples of such surface modifiers include silane-based surface modifiers (also known as silane coupling agents), titanate-based surface modifiers, and isocyanate-based surface modifiers, but are not particularly limited to these. Preferably, silane-based surface modifiers can be used. These surface modifiers can be used alone or in combination of two or more. As commercially available products of silane-based surface modifiers, for example, they can be obtained from Shin-Etsu Chemical Co., Ltd., Dow Corning Corporation, and Evonik Corporation. Silane-based surface modifiers are silane compounds having functional groups and hydrolyzable condensation groups in the molecule. Examples of functional groups include vinyl groups such as vinyl, methacryloxy, acryloxy, and styryl, amino groups, epoxy groups, mercapto groups, thioether groups, isocyanate groups, and halogens. Considering the high adhesiveness to glass, as the functional group, one or more selected from vinyl, amino, epoxy, methacryloxy, and acryloxy are preferred, and one or more selected from amino, methacryloxy, and epoxy are most preferred. These functional groups can be single or multiple in the molecule. These surface modifiers can be used singly or in combination of two or more. Examples of silane-based surface modifiers having vinyl as a functional group include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of silane coupling agents having styryl as a functional group include p-styryltrimethoxysilane. Examples of silane coupling agents having acryloxy as a functional group include 3-acryloxypropyltrimethoxysilane. Examples of silane coupling agents having methacryloxy as a functional group include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. Examples of silane coupling agents having epoxy as a functional group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Examples of silane coupling agents having amino as a functional group include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyl ethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, bis(3-trimethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)amine, and N-(n-butyl)-3-aminopropyltrimethoxysilane. The above are examples of those having methoxy and ethoxy as hydrolyzable condensation groups, but triisopropoxy and acetoxy can also be used.Particularly preferably, a silane-based surface modifier having one or more selected from methacryloxy, acryloxy, styryl, amino, epoxy, and mercapto groups as functional groups is used.

[0110] The insulating adhesive layer composition (hereinafter, also simply referred to as "composition") containing the above copolymer and the above monomer or polymer, and optionally containing a surface modifier can be prepared by a method known in the art, and the method is not particularly limited. For example, the preparation of the insulating adhesive layer composition can be carried out as described below. When the copolymer component is resinous, these surface modifiers can be mixed by a known kneading method, such as a twin-screw kneader, various rolls, various kneaders, etc. When the copolymer component is varnish-like, it can be mixed and dissolved by adding and stirring to the varnish.

[0111] For the insulating adhesive layer composition of the present embodiment, in addition to the aforementioned copolymer, the above monomer or polymer having a carboxyl group or an acid anhydride group, and optionally a surface modifier, it may independently contain the following curing agents, other resin components, monomers, fillers, flame retardants, and solvents.

[0112] <Curing agent>

[0113] As the curing agent that can be used in the insulating adhesive layer composition of the present embodiment, known radical generators and curing agents that have been conventionally used in the polymerization or curing of aromatic polyenes and aromatic vinyl compounds can be used. As such curing agents, radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators can be exemplified, but their types are not particularly limited. Radical polymerization initiators can be preferably used. In addition, hydrocarbon-based radical polymerization initiators that do not contain oxygen atoms or nitrogen atoms in their structures, such as 2,3-dimethyl-2,3-diphenylbutane, can also be preferably used. By using this hydrocarbon-based radical polymerization initiator to produce a cured body, a cured body with a low dielectric constant and a low dielectric loss tangent can be obtained. That is, if a curing agent that contains oxygen atoms or nitrogen atoms in its structure is used, the residue from the curing agent remaining in the cured body tends to deteriorate the dielectric properties of the cured body. By using this hydrocarbon-based radical polymerization initiator to produce a cured body, the original good low dielectric properties of the resin (copolymer) component that is the raw material of the cured body can be exhibited. It is preferably an organic peroxide-based (peroxide), azo-based polymerization initiator, etc., and can be freely selected according to uses and conditions. The catalog listing organic peroxides can be downloaded from the homepage of NOF Corporation, such as https: / / www.nof.co.jp / business / chemical / chemical-product01. In addition, organic peroxides are also described in the catalogs of FUJIFILM Wako Pure Chemical Corporation, Tokyo Chemical Industry Co., Ltd., etc. The curing agents that can be used in the present embodiment can be obtained from these companies. In addition, known photoinitiators that utilize light, ultraviolet rays, or radiation can also be used as curing agents. As the curing agent using a photoinitiator, a photo radical polymerization initiator, a photo cationic polymerization initiator, or a photo anionic polymerization initiator can be cited. Such photoinitiators can be obtained from, for example, Tokyo Chemical Industry Co., Ltd. In addition, curing can also be carried out using radiation or an electron beam itself. In addition, crosslinking and curing can be carried out using the heat of the raw materials contained without including a curing agent.

[0114] There is no particular limitation on the amount of the curing agent used. Generally, relative to 100 parts by mass of the composition, it is preferably 0.01 to 10 parts by mass. At this time, the composition takes the resin component other than the curing agent, solvent, and filler as 100 parts by mass. When using a curing agent such as a peroxide or an azo-based polymerization initiator, considering its half-life, curing treatment is carried out at an appropriate temperature and time. The conditions in this case are arbitrary depending on the curing agent, but generally, a temperature range of about 50°C to 200°C is appropriate.

[0115] The composition of the insulating adhesive layer of the present embodiment may also contain "other resin components", such as "one or more resins selected from hydrocarbon-based elastomers, polyphenylene ether-based resins, and aromatic polyene-based resins". The use ratio of the "other resin components" can be appropriately set according to the desired properties and is not particularly limited. In total of the "other resin components", it is preferably included in the range of 1 to 200 parts by mass relative to 100 parts by mass of the copolymer. By adding these other resin components, there is a tendency to easily obtain the effect of improving the mechanical properties of the cured product obtained from the present varnish.

[0116] <Hydrocarbon-based elastomer>

[0117] The amount of the hydrocarbon-based elastomer used in the insulating adhesive layer composition of the present embodiment can be appropriately set according to the desired properties and is not particularly limited. It is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, and most preferably 1 to 50 parts by mass relative to 100 parts by mass of the copolymer. The number average molecular weight of the hydrocarbon-based elastomer that can be preferably used in the composition of the present embodiment is preferably 100 or more and 100,000 or less, more preferably 1,000 or more and 4,500 or less. As the hydrocarbon-based elastomer that can be preferably used in the composition of the present embodiment, one or more elastomers selected from ethylene-based, propylene-based elastomers, conjugated diene polymers, block copolymers or random copolymers of aromatic vinyl compounds-conjugated dienes, and their hydrides (hydrogenated products) can be preferably exemplified, but are not particularly limited to these. As the ethylene-based elastomer, ethylene-octene copolymers, ethylene-α-olefin copolymers such as ethylene-1-hexene copolymers, EPR, EPDM, etc. can be mentioned. As the propylene-based elastomer, atactic polypropylene, polypropylene with low stereoregularity, propylene-α-olefin copolymers such as propylene-1-butene copolymers, etc. can be mentioned, but are not particularly limited to these. These hydrocarbon-based elastomers can be modified by introducing functional groups using compounds such as maleic anhydride.

[0118] As the conjugated diene polymer, polybutadiene, 1,2-polybutadiene can be cited, but not particularly limited to these. As the block copolymer or random copolymer of aromatic vinyl compound-conjugated diene system, and their hydrides (hydrogenated products), SBS, SIS, SEBS, SEPS, SEEPS, SEEBS, etc. can be exemplified, but not particularly limited to these. The 1,2-polybutadiene that can be preferably used can be obtained, for example, from Nippon Soda Co., Ltd. under the product names of liquid polybutadiene: B-1000, 2000, 3000. In addition, as the copolymer containing the 1,2-polybutadiene structure that can be preferably used, "Ricon100" of TOTAL CRAYVALLEY company can be exemplified. These aforementioned conjugated diene polymers and their hydrides can be modified by introducing functional groups using compounds such as maleic anhydride. For the single or multiple resins selected from these hydrocarbon elastomers, especially when it is in a liquid state (about 300,000 mPa·s or less) at room temperature (25°C), from the viewpoints of operability in the uncured state and molding processability (operability as a thermoplastic resin), with respect to 100 parts by mass of the copolymer, the usage amount is preferably in the range of 150 parts by mass or less, more preferably in the range of 1 to 30 parts by mass, and most preferably in the range of 1 to 20 parts by mass.

[0119] <Polyphenylene ether, polyether>

[0120] As the polyphenylene ether (also called "polyphenylene ether resin"), commercially available known polyphenylene ether can be used, and its type is not particularly limited. In addition, aromatic polyether (ELPAC HC-F series) of JSR Corporation can also be used. The number average molecular weight of the polyphenylene ether and polyether is arbitrary and can be appropriately set according to the desired properties, and is not particularly limited. Considering the molding processability of the composition, the number average molecular weight (Mn) is preferably 10,000 or less, and most preferably 5000 or less. The number average molecular weight is preferably 500 or more.

[0121] In addition, when added for the purpose of curing the insulating adhesive layer composition of the present embodiment, it is preferable that the molecular terminals of the polyphenylene ether are modified with functional groups. In addition, when added for the purpose of curing the composition of the present embodiment, it is preferable that a plurality of functional groups are present in one molecule of the polyphenylene ether. For example, a modified polyphenylene ether is preferable. Examples of the functional group include a radically polymerizable functional group, a functional group such as an epoxy group, and a radically polymerizable functional group is preferable. As the radically polymerizable functional group, a vinyl group is preferable. As the vinyl group, one or more selected from the group consisting of an allyl group, a (meth)acryloyl group, and an aromatic vinyl group are preferable, one or more selected from the group consisting of a (meth)acryloyl group and an aromatic vinyl group are more preferable, and an aromatic vinyl group is most preferable. That is, in the composition of the present embodiment, a difunctional polyphenylene ether in which both ends of the molecular chain are modified with a radically polymerizable functional group is particularly preferable. Examples of such a polyphenylene ether include Noryl (registered trademark) SA9000 of SABIC (a modified polyphenylene ether having methacryloyl groups at both ends, number average molecular weight: 2200), a difunctional polyphenylene ether oligomer (OPE-2St) manufactured by Mitsubishi Gas Chemical Company (a modified polyphenylene ether having vinylbenzyl groups at both ends, number average molecular weight: 1200), etc., but it is not particularly limited to these. In addition, allylated PPE of Asahi Kasei Corporation can also be used. Among them, the difunctional polyphenylene ether oligomer (OPE-2St) manufactured by Mitsubishi Gas Chemical Company can be preferably used. The amount of the polyphenylene ether used in the composition of the present embodiment can be appropriately set according to the desired properties and is not particularly limited, and is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, relative to 100 parts by mass of the copolymer.

[0122] <Aromatic polyene resin>

[0123] The aromatic polyene resin contains a divinylbenzene-based reactive multi-branched copolymer (PDV, ODV) manufactured by NIPPON STEEL Chemical & Material Co., Ltd. Such a multi-branched copolymer is described, for example, in the literature "Synthesis of polyfunctional aromatic vinyl copolymers and development of novel IPN-type low dielectric loss materials using the same" (Masanao Kawabe et al., Journal of Japan Institute of Electronics Packaging p125, Vol. 12 No. 2 (2009)), US Patent US8404797B2, International Publication No. 2018 / 181842, etc. In addition, as the aromatic polyene resin, an aromatic polyene polymer resin having the above-mentioned aromatic polyene monomer as a main structural unit can also be mentioned. The amount of the aromatic polyene resin used in the composition of the present embodiment can be appropriately set according to the desired performance and is not particularly limited. It is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, and most preferably 1 to 50 parts by mass relative to 100 parts by mass of the copolymer. The use of the amount of the aromatic polyene resin within these preferred numerical ranges is effective for adjusting the mechanical properties of the cured product obtained from the composition and is preferred to prevent a decrease in the adhesiveness to other members and a decrease in toughness. If it is 200 parts by mass or less, there is a tendency not to exhibit brittleness and to improve the adhesiveness to other members.

[0124] <Other monomers>

[0125] In the insulating adhesive layer composition of the present embodiment, other monomers other than the aforementioned "monomers" may also be included. As such other monomers, for example, "aromatic vinyl compounds" such as styrene described above, "aromatic polyenes" such as divinylbenzene, and "aromatic vinylidene compounds" may be appropriately added. An aromatic vinylidene compound is a compound having a single aromatic ring having 9 to 30 carbon atoms or a plurality of fused aromatic rings and a vinylidene group. Examples of such aromatic vinylidene compounds include indenes, β-substituted styrenes, and acenaphthylenes. As the aforementioned indenes, indene, various alkyl-substituted indenes, and phenyl-substituted indenes can be cited. Among the β-substituted styrenes, β-alkyl-substituted styrenes such as β-methylstyrene or phenyl-substituted styrenes can be cited. As the acenaphthylenes, acenaphthylene, various alkyl-substituted acenaphthylenes, and various phenyl-substituted acenaphthylenes can be cited. The aforementioned aromatic vinylidene compounds may be used alone with the compounds exemplified above, or two or more thereof may be used in combination. The aforementioned aromatic vinylidene compounds preferably have a boiling point of 175 °C or higher at normal pressure. From the viewpoints of industrial availability and radical polymerizability, acenaphthylene is most preferred. The amount of these "other monomers" that can be used in the insulating adhesive layer composition is preferably 1 to 100 parts by mass, more preferably 1 to 30 parts by mass, based on 100 parts by mass of the copolymer.

[0126] <Filler>

[0127] In this insulating adhesive layer composition, known inorganic or organic fillers may be added as required. These fillers can be added for the purpose of controlling the coefficient of thermal expansion, controlling the thermal conductivity, and reducing the cost. In addition, the amount used is arbitrary depending on the purpose. In particular, when adding inorganic fillers, it is preferable to use known surface modifiers such as silane coupling agents. In particular, when aiming for a composition with excellent low dielectric constant and low dielectric loss, as the inorganic filler, one or more selected from the group consisting of boron nitride (BN) and silica are preferred, and silica is more preferred. As silica, fused silica is preferred. From the viewpoint of low dielectric properties, it is preferable to use less than 500 parts by mass of the filler, and more preferably less than 400 parts by mass of the filler, based on 100 parts by mass of the copolymer. In addition, in order to improve and enhance the low dielectric properties (low dielectric constant, low dielectric loss tangent), hollow fillers or fillers with a porous shape can be added. The average particle size (d50) of the filler can be appropriately set according to the desired properties and is not particularly limited. It is preferably 0.01 to 100 μm, more preferably 0.1 to 10 μm, and most preferably 0.3 to 1 μm. It should be noted that d50 is the value at which the cumulative volume is 50%. The average particle size (d50) can be determined from the volume particle size distribution curve obtained by a laser diffraction particle size analyzer (Beckman Coulter "Model LS-230"). The specific surface area of the filler can be appropriately set according to the desired properties and is not particularly limited. It is preferably 1 to 30 m 2 / g, and more preferably 3 to 10 m 2 / g. The specific surface area can be measured by the following method. Fill 1 g of the sample in the measurement cell, and measure the specific surface area using a Macsorb HM model-1201 fully automatic specific surface area measuring device (BET single point method) manufactured by Mountech. The degassing conditions before measurement are 200 °C for 10 minutes. The adsorbed gas is nitrogen. The volume ratio of the resin component to the filler is in the range of 98 to 15:2 to 85, preferably in the range of 85 to 15:15 to 85, more preferably in the range of 85 to 30:15 to 70, and can be further preferably in the range of 80 to 60:20 to 40.

[0128] Alternatively, organic fillers such as high molecular weight polyethylene or ultra-high molecular weight polyethylene can be used instead of inorganic fillers. For organic fillers, from the viewpoint of heat resistance, it is preferable that they are crosslinked themselves, and they are preferably incorporated in the form of fine particles or powder. These organic fillers can suppress the increase in dielectric constant and dielectric loss tangent.

[0129] On the other hand, by mixing and dispersing a high-dielectric constant insulator filler having a dielectric constant of preferably 4 to 10,000, more preferably 5 to 10,000 at 1 GHz in the present insulating adhesive layer composition, it is possible to produce an insulating cured product that suppresses the increase in the dielectric loss tangent (dielectric loss) and has a high dielectric constant of preferably 4 to 20. By increasing the dielectric constant of the film formed from the insulating cured product, miniaturization of the circuit and high capacitance of small-capacitance capacitors can be achieved, which can contribute to miniaturization of high-frequency electrical components, etc. An insulating layer with a high dielectric constant and a low dielectric loss tangent is suitable for applications such as large-capacitance capacitors, inductors for resonance circuits, filters, and antennas. Examples of the high-dielectric constant insulator filler used in the present embodiment include inorganic fillers or metal particles subjected to insulation treatment, but are not particularly limited thereto. Specific examples are known high-dielectric constant inorganic fillers such as barium titanate and strontium titanate, and other examples are specifically described in, for example, Japanese Patent Laid-Open No. 2004-087639.

[0130] <Flame retardant>

[0131] In the insulating adhesive layer composition, a flame retardant can also be used. From the viewpoint of maintaining a low dielectric constant and a low dielectric loss tangent, preferred flame retardants are one or more selected from organic phosphorus-based, bromine-based flame retardants such as phosphate esters or their condensates, and red phosphorus, but are not particularly limited thereto. In particular, among phosphate esters, compounds having multiple xylyl groups in the molecule are preferred from the viewpoints of flame retardancy and low dielectric loss tangent.

[0132] Furthermore, in addition to the flame retardant, as a flame retardant aid, antimony-based compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate, or nitrogen-containing compounds such as melamine, triallyl-1,3,5-triazine-2,3,4-(1H,3H,5H)-trione, and 2,4,6-triallyloxy-1,3,5-triazine can also be added. The total amount of these flame retardants and flame retardant aids can be appropriately set according to the desired performance and is not particularly limited. Usually, it is preferably 1 to 100 parts by mass relative to 100 parts by mass of the composition. In addition, 30 to 200 parts by mass of the aforementioned polyphenylene ether (PPE)-based resin having a low dielectric constant and excellent flame retardancy can be used relative to 100 parts by mass of the flame retardant.

[0133] The present insulating adhesive layer composition may further contain a solvent. In addition, among these compositions, a composition that is especially liquid by containing a solvent is called a varnish.

[0134] <Solvent>

[0135] Regarding the insulating adhesive layer composition, an appropriate solvent can be added as needed. Additionally, its usage amount is not particularly limited. The solvent is used to adjust the viscosity and fluidity of the composition. Especially when the composition in this embodiment is in the form of a varnish, a solvent is preferably used. When the boiling point of the solvent is high under atmospheric pressure, that is, when the volatility is low, the thickness of the coated film becomes uniform. Therefore, a solvent having a boiling point of a certain degree or more is preferred. The preferred boiling point is about 100 °C or more, more preferably 110 °C or more and 300 °C or less under atmospheric pressure. As the solvent, substances known in the art can be used, and there is no particular limitation. For example, cyclohexane, toluene (boiling point: 110 °C), ethylbenzene, xylene, mesitylene, tetralin, acetone, limonene, mixed alkanes, mixed aromatic solvents, etc. can be used. The usage amount of the solvent used in the composition of this embodiment can be appropriately set according to the desired performance and is arbitrary. Relative to 100 parts by mass of the copolymer, it is preferably 5 to 500 parts by mass, more preferably 10 to 300 parts by mass, and most preferably 50 to 250 parts by mass.

[0136] <Varnish>

[0137] For the varnish of this embodiment, by adjusting the composition and molecular weight of the copolymer used, adding a liquid monomer, solvent, or adding a liquid flame retardant within a certain amount or more in the range of this embodiment, it can be shown as a viscous liquid at room temperature or under heating conditions of 100 °C or below. For example, it has a viscosity of several hundred thousand mPa·s or less, preferably 2000 mPa·s or less, more preferably 1000 mPa·s or less, and most preferably 500 mPa·s or less at room temperature. Here, the viscosity can be measured using a rotational viscometer, for example. Specifically, the varnish of this embodiment can be coated, impregnated, filled, or dropped onto other raw materials by an appropriate method, and the solvent is removed to form a molded body. Furthermore, multi-layerization is carried out, and it is cured by heat or light to obtain the target cured product.

[0138] The insulating adhesive layer composition and varnish of this embodiment can contain additives commonly used in resins in the art, such as antioxidants, weathering agents, light stabilizers, lubricants, solubilizers, antistatic agents, etc., within the range that does not hinder the desired effects and purposes. The composition and varnish of this embodiment can be obtained by mixing, dissolving, or melting the aforementioned various additives, and any known method can be used for mixing, dissolving, and melting.

[0139] <Preferred Structure of Multi-Layer Structure>

[0140] In a preferred embodiment, a part or all of this multi-layer structure can have Figures 1A - 1BThe structure shown, or its repeating structure. The area of each layer included in this multi-layer structure may not be constant, for example, it may be divided into island shapes, or recesses may be provided (in this drawing, a case where the area of the metal foil is different from the area of other layers is also shown as a modified example). In addition, one or more of the layers included in this multi-layer structure may have through holes or via holes (through hole via, Interstitial via, blind via, buried via, etc.). In this specification, these holes are not considered in terms of the definition of the layer constitution of this multi-layer structure (in the above drawing, the existence of the holes is depicted in a way that omits them). The thickness of the insulating adhesive layer of this embodiment can be appropriately set according to the desired performance, is arbitrary, and is preferably in the range of 10 μm to 1 mm.

[0141] <Manufacturing method of the multi-layer structure>

[0142] This insulating adhesive layer can exhibit the properties of a thermoplastic resin before curing. Therefore, without causing crosslinking, it can be formed into a shape such as a sheet in a substantially uncured state by known thermoplastic resin molding methods such as extrusion molding, injection molding, compression molding, blow molding, etc., and can be bonded to other layers. Then, after laminating with a metal foil and an insulating resin layer, it can be crosslinked (cured). In this specification, this method is referred to as the thermoplastic resin method. Additionally, when the composition is supplied as a varnish, after coating on a metal foil or an insulating resin sheet, the solvent can be removed by heating, decompression, air drying, etc. under substantially uncured conditions to form a multi-layer sheet or a film-like uncured molded body. Then, it is laminated with other layers, and if necessary, bonded by heating and pressing under non-crosslinking conditions, and then crosslinked (cured). It is also possible to impregnate a porous substrate, fabric, or non-woven fabric with the varnish of this embodiment, remove the solvent, obtain an uncured composite sheet, laminate it with other layers, and if necessary, bond it by heating and pressing under non-crosslinking conditions and crosslink (cure) it as a multi-layer structure. In this specification, this method is referred to as the varnish method. These uncured sheets are preferably uncured to the extent that they can maintain the sheet shape and uncured to the extent that they can be bonded and cured to a metal foil and an insulating resin layer by curing later. That is, the uncured state mentioned here also includes the concept of a completely uncured state where no curing has occurred and a semi-cured state where partial curing has occurred. The degree of curing of the composition can be quantitatively measured using a known dynamic viscoelasticity measurement method (DMA, Dynamic Mechanical Analysis). In the above manufacturing method of the multi-layer structure, an example of using a metal foil such as a copper foil is shown, but as a method without using a metal foil, there is also a method of forming a metal foil layer by plating. Examples of such methods include subtractive processes, full-additive processes, and semi-additive processes. The full-additive process and the semi-additive process are methods of depositing a metal foil layer and a circuit pattern only in necessary parts on a resin layer by electrolytic plating. In particular, the so-called semi-additive process is the following manufacturing method: after forming a pattern of a plating resist on a resin sheet on which a metal thin film serving as a plating seed layer is deposited by sputtering or the like, electrolytic plating is performed to grow a circuit pattern formed of a metal foil such as a copper foil into a resin sheet shape.

[0143] <Specific manufacturing methods of the multi-layer structure>

[0144] Figures 2 - 5Examples of specific manufacturing methods of the present multi-layer structure are shown. These are merely examples of manufacturing methods, and the multi-layer structure of the present embodiment is not limited to these manufacturing examples. The following lamination methods may be the aforementioned thermoplastic resin method or the varnish method. The thicknesses of the respective layers and the metal foil are not limited and are arbitrary, and vary depending on uses such as microstrip lines and other high-frequency signal transmission lines, FCCL, antennas, etc. Additionally, the metal foil (circuit pattern) layer may be provided by various plating methods without using a metal foil.

[0145] Figure 2 Examples of methods for manufacturing Figure 1A a modified example of the structure (1) are shown. It should be noted that it can be understood that the structure (1) of the non-modified example can also be fabricated by the same method (the same applies hereinafter). First, a metal foil is laminated on the insulating adhesive layer side of a multi-layer sheet including an insulating resin layer and an insulating adhesive layer, and heat pressing is performed under conditions where the insulating adhesive layer is semi-cured but not fully cured (temperature, pressure, etc., the same applies hereinafter) as needed. Alternatively, it may be semi-cured or fully cured under appropriate conditions here. It should be noted that "semi-cured" in this specification refers to a state that can be further cured by subsequent heating. A pattern is formed by etching a part of the metal foil of the obtained multi-layer sheet with the metal foil. The obtained multi-layer structure is heat pressed and cured under conditions where the insulating adhesive layer is cured as needed. Thereby, the structure (1) is obtained.

[0146] Figure 3 Examples of methods for manufacturing Figure 1A a modified example of the structure (1) are shown. First, an insulating adhesive layer is laminated on one surface (which may be a roughened surface or a smooth surface) of the metal foil, and heat pressing is performed under conditions where the complete curing of the insulating adhesive layer is not caused, or under semi-cured conditions (that is, it can be considered that the above-mentioned RCC is fabricated here). An insulating resin sheet is laminated on the insulating adhesive layer side of the obtained RCC. At this time, heat pressing may also be performed under conditions where the insulating adhesive layer is cured to cure it (etching can also be performed in the same manner as above. The same applies hereinafter). In this way, the structure (1) can also be obtained.

[0147] Figure 4 Examples of methods for manufacturing Figure 1B a modified example of the structure (2) are shown. First, insulating adhesive layers are respectively laminated on both surfaces of the insulating resin layer, and heat pressing is performed under conditions where the insulating adhesive layer is semi-cured but not fully cured (fabrication of the multi-layer sheet). Metal foils are respectively laminated on both surfaces on the insulating adhesive layer side of the obtained multi-layer sheet, and the obtained multi-layer structure is heat pressed and cured under conditions where the insulating adhesive layer is cured. Thereby, the structure (2) is obtained.

[0148] Figure 5 Another example of a method showing a modified example of the structure (2) to be manufactured. First, an insulating adhesive layer is laminated on one surface of a metal foil (which can be a roughened surface or a smooth surface). If necessary, heat pressing (manufacture of RCC) is performed under conditions where the insulating adhesive layer is semi-cured but not fully cured. Thus, a pair of RCCs are manufactured. The obtained multilayer structure is heat pressed and cured under conditions where the insulating adhesive layer is cured by laminating an insulating resin sheet in such a manner that it is sandwiched between the insulating adhesive layers of two pieces of RCC. In this way, the structure (2) can also be obtained. Figure 1B

[0149] <Curing>

[0150] The curing of the above-mentioned multilayer structure can be carried out by using a known method with reference to the curing conditions (temperature, time, pressure, light) of the raw materials and curing agents contained therein. When the curing agent used is a peroxide, generally, the curing conditions such as heating conditions can be determined with reference to the half-life temperature and the like disclosed for each peroxide.

[0151] <Cured product of the multilayer structure>

[0152] The cured product of the multilayer structure of the present embodiment can be fully cured. Here, the gel part (gel fraction) of the cured product of the insulating adhesive layer measured in accordance with ASTM is not particularly limited and can be 95% by mass or more. In addition, the dielectric constant of the cured product of this insulating adhesive layer in the measurement range of 10 to 50 GHz, particularly preferably under the condition of 10 GHz, is not particularly limited, preferably 3.0 or less and 2.0 or more, more preferably 2.8 or less and 2.0 or more, and most preferably 2.5 or less and 2.0 or more. The tangent of the dielectric loss angle of the cured product of this insulating adhesive layer in the measurement range of 10 to 50 GHz, particularly preferably under the condition of 10 GHz, is not particularly limited, preferably 0.003 or less and 0.0005 or more, more preferably 0.002 or less and 0.0008 or more. In addition, the volume resistivity of the obtained cured product of the insulating adhesive layer is not particularly limited and can be preferably 1×10 15 Ω·cm or more. In addition, the water absorption rate of the cured product of the insulating adhesive layer is not particularly limited and can be 0.1% by mass or less. The water absorption rate is preferably less than 0.1% by mass, and if within this preferred numerical range, it is preferred as an electrical insulating material. These values are, for example, particularly preferred values as electrical insulating materials for high frequencies of 3 GHz or more.

[0153] The cured product of the insulating adhesive layer of this multilayer structure can exhibit high adhesiveness to both the smooth surface and the roughened surface of the metal foil for wiring (such as copper foil or aluminum foil). Its adhesive strength is preferably 0.8 N / mm or more, more preferably 1.0 N / mm or more, and even more preferably greater than 1.0 N / mm. Therefore, it is preferred as the insulating adhesive layer of this multilayer structure. In addition, the cured product of the insulating adhesive layer of this multilayer structure can also exhibit high adhesiveness to each resin of the insulating resin layer. As the resin of the insulating resin layer, polyimide (PI) and modified polyimide (MPI) can exhibit high adhesiveness, and thus are particularly preferred.

[0154] In another embodiment, a composition can also be provided, which contains an olefin - aromatic vinyl compound - aromatic polyene copolymer as the main component, and contains 0.001 to 5 parts by mass of a monomer or polymer having a carboxyl group or an acid anhydride group relative to the olefin - aromatic vinyl compound - aromatic polyene copolymer. The preferred olefin - aromatic vinyl compound - aromatic polyene copolymer is as described above, and the preferred monomer or polymer is also as described above. This composition can provide a cured product having high adhesive force to the roughened surface and the smooth surface of the metal foil, and can also provide a cured product having high adhesive force to the insulating resin layer.

[0155] In a certain embodiment, a multilayer structure can also be provided, which contains a cured product of the following composition. This composition contains an olefin - aromatic vinyl compound - aromatic polyene copolymer as the main component, and contains 0.001 to 5 parts by mass of a monomer or polymer having a carboxyl group or an acid anhydride group relative to the olefin - aromatic vinyl compound - aromatic polyene copolymer. In addition, a high - frequency signal transmission line such as a microstrip line, a multilayer FCCL, or an antenna containing this multilayer structure can also be provided. The insulating adhesive layer containing the cured product of this composition is characterized by the aforementioned good low - dielectric properties and high adhesiveness to metal foils such as copper foil and the insulating resin layer.

[0156] In addition, the insulating adhesive layer of this embodiment exhibits good adhesiveness as described above. However, regarding the adhesion between the insulating adhesive layer and the metal foil and the insulating resin layer, there is no problem using known adhesive formulations. For example, methods such as pre - corona - treating or plasma - treating the resin layer to activate the surface and roughening the surface by forming irregularities can be exemplified. In addition, the insulating adhesive layer of this embodiment can exhibit better adhesiveness by adding the aforementioned surface modifier. Especially when the surface of these resin sheets is treated by surface treatments such as corona treatment or plasma treatment as described above, higher adhesiveness can be expected.

[0157] Examples

[0158] Synthesis examples, examples, and comparative examples are given below to illustrate the features of the present invention more specifically, but the present invention is not limited by any of them. That is, materials, amounts used, ratios, treatment contents, treatment steps, etc. shown in the following synthesis examples and examples can be appropriately changed as long as they do not depart from the gist of the present invention. In addition, various manufacturing conditions and values of evaluation results in the following examples have the meaning of preferred upper limit values or preferred lower limit values in the embodiments of the present invention, and the preferred numerical range can also be a range defined by a combination of the aforementioned upper limit value or lower limit value and the values in the following examples or the values between the examples. In addition, the analysis of the copolymers obtained in the synthesis examples and comparative synthesis examples was carried out by the following methods.

[0159] <Analysis of Copolymer Structure>

[0160] The determination of the content of vinyl units derived from ethylene, hexene, styrene, and divinylbenzene in the copolymer was carried out by 1 H-NMR or 13 C-NMR, based on the peak area intensity attributed to each. The sample was dissolved in deuterated 1,1,2,2-tetrachloroethane, and the measurement was carried out at 50 to 130 °C.

[0161] <Number-Average Molecular Weight (Mn)>

[0162] For the molecular weight of the copolymer, GPC (gel permeation chromatography) was used to determine the number-average molecular weight (Mn) in terms of standard polystyrene. The measurement was carried out under the following conditions.

[0163] Column: Two TSK-GEL MultiporeHXL-M (manufactured by TOSOH Corporation) were connected in series and used.

[0164] Column temperature: 40 °C

[0165] Solvent: THF

[0166] Liquid delivery flow rate: 1.0 ml / min.

[0167] Detector: RI detector

[0168] <Gel Fraction>

[0169] According to ASTM D2765-84, the gel fraction (mass %) of the cured product (cured sheet) of the insulating adhesive layer, which is the component insoluble in boiling toluene, was determined.

[0170] <Water Absorption>

[0171] In accordance with ASTM D570-98, the water absorption (mass %) of the cured product (cured sheet) of the insulating adhesive layer after being immersed in pure water at 23 °C for 24 hours was measured.

[0172] <Dielectric Constant and Dielectric Loss (Dielectric Loss Tangent)>

[0173] Regarding the dielectric constant and the dielectric loss tangent, in accordance with JIS K6471, the cavity resonator perturbation method (Agilent Technologies Inc. model 8722ES network analyzer, cavity resonator manufactured by Kanto Electronic Application Development Co., Ltd.) was used, and a sample of 1 mm × 1.5 mm × 80 mm cut from the sheet was used to measure the values under the conditions of 23°C and 10 GHz.

[0174] <Adhesive Strength (Peel Strength) between Insulating Adhesive Layer and Copper Foil>

[0175] The copper foil used was electrolytic copper foil with a roughened surface and a smooth surface on the front and back (manufactured by Mitsui Mining & Smelting Co., Ltd. (VSP series, TQ-M7-VSP), thickness 12 μm, surface roughness Rz of the roughened surface 1.1 μm). The copper foil was placed on a Teflon (registered trademark) sheet with the smooth surface of the copper foil facing up. Next, several uncured sheets of the insulating adhesive layer were overlapped on the smooth surface of the copper foil, and further, a SUS mold frame (thickness 0.2 mm) was placed thereon, and a Teflon sheet was further overlapped thereon to form a laminated structure. Here, the insulating adhesive layers used were the uncured sheets of the following Examples and Comparative Examples. Then, a load with a surface pressure of 5 MPa was applied to the obtained laminated structure using a press, and heat treatment and hot press bonding were performed under the conditions of 120°C for 30 minutes, 150°C for 30 minutes, and then 200°C for 120 minutes to cure the insulating adhesive layer. After curing, the Teflon sheet and the mold frame were removed to obtain a multilayer structure in which the insulating adhesive layer (cured sheet) was bonded and cured to the smooth surface of the copper foil. In addition, the measurement of the adhesive strength between the insulating adhesive layer (cured sheet) and the copper foil was carried out in accordance with Japanese Industrial Standard (JIS) C6471:1995, and the peel was evaluated by 180° peel. It should be noted that for the measurement of the adhesive strength, a strip-shaped test piece with a width of 10 mm was cut out from the obtained multilayer structure, and using Strograph VE1D (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the peel strength of the copper foil was measured in the 180-degree direction at a tensile speed of 50 mm / minute in an environment of 23°C and 50% RH.

[0176] In addition, the copper foil was placed on the Teflon sheet with the roughened surface of the copper foil facing up, and several uncured sheets of the insulating adhesive layer were overlapped on the roughened surface of the copper foil, and otherwise, the same operations as the above method were carried out, whereby a multilayer structure in which the insulating adhesive layer (cured sheet) was bonded and cured to the roughened surface of the copper foil was obtained. Then, the adhesive strength between the insulating adhesive layer (cured sheet) and the copper foil was measured in the same manner.

[0177] <Adhesion strength (peel strength) between insulating adhesive layer and insulating resin layer>

[0178] As the insulating resin layer (polyimide (PI) sheet), Kapton (registered trademark) manufactured by DU PONT-TORAY Co., Ltd. with a thickness of 0.2 mm was used. The Kapton sheet was set on a mirror SUS plate, and several uncured sheets as the insulating adhesive layer were overlapped on the Kapton sheet. Further, a SUS mold frame (thickness: 0.5 mm) was set thereon, and a Teflon sheet was further overlapped thereon to form a laminated structure. Here, the insulating adhesive layers used were the uncured sheets of the following Examples and Comparative Examples. Then, a load with a surface pressure of 5 MPa was applied to the obtained laminated structure by a press, and heat treatment was performed under the conditions of 120°C for 30 minutes, 150°C for 30 minutes, and then 200°C for 120 minutes, followed by hot pressing to cure the insulating adhesive layer. After curing, the Teflon sheet and the mold frame were removed to obtain a multilayer structure in which the polyimide sheet as the insulating resin layer was adhesively cured with the insulating adhesive layer (cured sheet). The adhesion strength between the insulating adhesive layer (cured sheet) and the insulating resin layer was measured in the same manner as above according to Japanese Industrial Standard (JIS) C6471:1995, and the peel was evaluated by 180° peel.

[0179] <Manufacture of copolymer>

[0180] (Synthesis Examples P-1, P-2)

[0181] Referring to the manufacturing methods described in Japanese Unexamined Patent Application Publication No. 2009-161743 and Japanese Unexamined Patent Application Publication No. 2010-280771, racemic-dimethylmethylenebis(4,5-benzo-1-indenyl)zirconium dichloride (structure shown in the following formula (1)) as a catalyst, modified methylaluminoxane (Tosoh Finechem Co., Ltd., MMAO-3A toluene solution) as a cocatalyst, cyclohexane as a solvent, styrene, divinylbenzene, ethylene, and 1-hexene as needed were used, and polymerization was carried out in a 10-L autoclave equipped with a stirrer and a heating / cooling jacket. 1-Isopropanol was added to the obtained polymerization solution, and then a large amount of methanol was added to recover the copolymer. The copolymer was air-dried and further vacuum-dried at 30°C for one day and night to obtain copolymers P-1 and P-2. The composition and number-average molecular weight of the copolymer are shown in Table 1.

[0182] Formula (1)

[0183] [Chemical formula 1]

[0184]

[0185] (Synthesis Example P-3)

[0186] Referring to the manufacturing methods described in Japanese Patent Laid-Open Nos. 9-40709, 9-309925, 2009-161743, and 2010-280771, polymerization was carried out using dibenzylidene(1-indenyl)(cyclopentadienyl)zirconium dichloride (the structure is shown in the following formula (2)) as a catalyst, modified (modified) methylaluminoxane (manufactured by Tosoh Finechem Corporation, MMAO-3A toluene solution) as a cocatalyst, cyclohexane as a solvent, styrene, divinylbenzene, and ethylene as raw materials, in a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 1-Isopropanol was added to the obtained polymerization solution, and then a large amount of methanol was added to recover the copolymer. The copolymer was thinly spread in a large container and vacuum-dried at 30 °C for two days and nights. The composition and number-average molecular weight of copolymer P-3 are shown in Table 1.

[0187] Formula (2)

[0188] [Chemical Formula 2]

[0189]

[0190] In addition, other raw materials are as described below.

[0191] Regarding the difunctional polyphenylene ether oligomer (OPE-2St, number-average molecular weight of 1200), the toluene solution product manufactured by Mitsubishi Gas Chemical Company was further diluted with toluene, a large amount of methanol was further added, methanol precipitation was carried out, and after air drying, vacuum drying was carried out to obtain a powdery polyphenylene ether oligomer for use. As 1,2-polybutadiene, “B-3000” manufactured by Nippon Soda Co., Ltd. was used, with a number-average molecular weight of 3200 and a viscosity of 210 Poise (21000 mPa·s, 45 °C). Maleic anhydride was used with a reagent purity of 99.0% or more manufactured by Tokyo Chemical Industry Co., Ltd. The silane coupling agent used was KBM-503 (3-methacryloxypropyltrimethoxysilane) manufactured by Shin-Etsu Silicone Co., Ltd. The curing agent used was Perhexyne 25B (organic peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne) manufactured by NOF Corporation.

[0192] [Table 1]

[0193]

[0194] [Table 2]

[0195]

[0196] ※With respect to the total of 100 parts by mass of the resin raw materials other than the curing agent, solvent, and silane

[0197] coupling agent, and filler, 1 part by mass was added

[0198] (Example 1)

[0199] (Example 1)

[0200] Using a container equipped with a heating and cooling jacket and stirring blades, P-1 (ethylene-styrene-divinylbenzene copolymer) obtained in the synthesis example, a solvent (toluene), and maleic anhydride were heated to about 40 °C in the proportions shown in Table 2 and stirred to dissolve. Further, 1 part by mass of a curing agent was added with respect to 100 parts by mass of the resin components other than the curing agent, solvent, and silane coupling agent, dissolved, and stirred and mixed to obtain a varnish-like composition. The obtained composition was poured into a silicon mold frame (the frame part has a length of 7 cm, a width of 7 cm, and a thickness of 0.5 mm, 1.0 mm, or 2.0 mm) placed on a Teflon (registered trademark) sheet on a glass plate. After air drying, it was further dried in a vacuum dryer at 60 °C for 3 hours or more to obtain an uncured sheet (insulating adhesive layer) with a thickness of about 0.5 mm. Then, the obtained uncured sheet was placed in a SUS mold frame equipped with a Teflon sheet, and using a press, it was heat-treated under a surface pressure load of 5 MPa at 120 °C for 30 minutes, 150 °C for 30 minutes, and then 200 °C for 120 minutes to cure it, obtaining a cured sheet (cured product of the insulating adhesive layer) with a thickness of about 0.5 mm except for the Teflon sheet and the SUS mold frame.

[0201] (Examples 2 to 4, Comparative Examples 1 and 2)

[0202] Compositions were prepared according to the formulations in Table 2 (the units in the table are parts by mass). Using the obtained compositions respectively, except for this, the same steps as in Example 1 were carried out to obtain uncured sheets and cured sheets of the compositions of Examples 2 to 4 and Comparative Examples 1 to 2.

[0203] The gel fraction, dielectric constant, dielectric loss tangent, and water absorption rate of the cured sheet are shown in Table 2. In addition, the adhesive strengths between the roughened surface of the copper foil and the insulating adhesive layer, between the smooth surface of the copper foil and the insulating adhesive layer, and between the insulating resin (polyimide) layer and the insulating adhesive layer, which were obtained by the aforementioned method, were measured respectively, and the results are shown in Table 2. Here, the insulating adhesive layer to be measured is a cured product (cured sheet) obtained by curing the uncured sheets of the examples and comparative examples. In the case of the examples, the cured product of the insulating adhesive layer exhibited good low dielectric constant, low dielectric loss tangent value, gel fraction, and water absorption rate. In addition, in the case of the examples, when the adhesive strengths at the interfaces of the roughened surface of the copper foil, the smooth surface of the copper foil, and the polyimide and the insulating adhesive layer were measured respectively, the adhesive strengths were too high, showing values of 1 N / mm or more, and as a result, fracture (material rupture), elongation of the resin part, or fracture (material rupture) of the copper foil occurred. That is, in these cases, the adhesive strength was 1 N / mm or more. In contrast, in Comparative Examples 1 and 2, the adhesive strengths between the smooth surface of the copper foil and the insulating adhesive layer showed values of 0.4 N / mm and 0.3 N / mm, respectively. In addition, the adhesive strengths between the insulating resin (polyimide) layer and the insulating adhesive layer showed values of 0.1 N / mm and 0.2 N / mm, respectively. That is, it was confirmed that the composition of the insulating adhesive layer according to the present example can provide a cured product that exhibits high adhesive strength to both the smooth surface of the copper foil, the roughened surface of the copper foil, and the polyimide as the insulating resin layer.

[0204] (Example 5)

[0205] Fabricate Figure 1A The cured product of the multilayer structure of the structure (1) shown. Here, as the insulating resin layer, a polyimide (PI) sheet is used; Kapton (registered trademark) manufactured by DU PONT-TORAY Co., Ltd., with a thickness of 0.2 mm. As the insulating adhesive layer, the uncured sheet obtained in Example 1 (with a thickness of about 0.5 mm) is used. The copper foil is the same as above, and an electrolytic copper foil manufactured by Mitsui Mining & Smelting Co., Ltd. (VSP series, TQ-M7-VSP) is used.

[0206] A copper foil is placed on a smooth SUS plate with the roughened surface of the copper foil facing upward. Next, the uncured sheet of Example 1 is placed on the roughened surface of the copper foil, and then the above-mentioned polyimide sheet is placed on the uncured sheet. Then, a Teflon sheet is placed on the polyimide sheet to form a laminated structure. At this time, a part of a thin Teflon sheet is inserted between the end portions between the roughened surface of the copper foil and the uncured sheet and between the uncured sheet and the polyimide sheet. After curing, the inserted Teflon sheets are respectively withdrawn, thereby preparing non-bonded end portions as the starting points of the tensile test. Then, using a hot press, the obtained laminated structure is heated and pressed under the condition of not using a mold frame. Heat treatment and thermocompression bonding are carried out under the conditions of a pressing pressure of about 1 MPa for the surface pressure, 120 °C for 30 minutes, and then 200 °C for 120 minutes to cure the insulating adhesive layer. After curing, the Teflon sheet is removed to obtain a cured product of the multi-layer laminate. Since no mold frame is provided, the thickness of the cured insulating adhesive layer becomes about 0.2 mm. In the cured product of the multi-layer structure, the peel strength between the copper foil and the insulating adhesive layer and the peel strength between the insulating adhesive layer and the insulating resin layer are both 1 N / mm or more.

[0207] (Example 6)

[0208] Fabricate Figure 1B A cured product of the multi-layer structure of the structure (2) shown. Here, the insulating resin layer uses a polyimide (PI) sheet; Kapton (registered trademark) manufactured by DU PONT-TORAY Co., Ltd., with a thickness of 0.2 mm. As the insulating adhesive layer, the uncured sheet obtained in Example 1 (thickness of about 0.5 mm) is used. The copper foil is the same as above, using an electrolytic copper foil manufactured by Mitsui Mining & Smelting Co., Ltd. (VSP series, TQ-M7-VSP).

[0209] A copper foil and the uncured sheet of Example 1 are sequentially overlapped on a smooth SUS plate, and a moderate load is applied at room temperature to make them fit tightly to fabricate a pair of RCCs. The insulating resin layer is clamped on the adhesive layer side of the pair of RCCs. At this time, a part of a thin Teflon sheet is inserted between the end portions of each layer. After curing, the inserted Teflon sheets are respectively withdrawn, thereby preparing non-bonded end portions as the starting points of the tensile test. Then, using a hot press, the obtained laminated structure is heated and pressed under the condition of not using a mold frame. Heat treatment and thermocompression bonding are carried out under the conditions of a pressing pressure of about 1 MPa for the surface pressure, 120 °C for 30 minutes, and then 200 °C for 120 minutes to cure the insulating adhesive layer. After curing, the Teflon sheet is removed to obtain Figure 1BThe cured product of the multilayer laminate of the structure (2) shown. Since no mold frame is provided, the thickness of the cured insulating adhesive layer becomes a thickness of about 0.2 mm. The peel strength between the layers of the cured product of the multilayer structure was measured, and the results were all 1 N / mm or more.

[0210] (Example 7)

[0211] Fabricate Figure 3 The part corresponding to RCC (resin-coated copper foil) in the figure shown. As the copper foil, electrolytic copper foil manufactured by Mitsui Mining & Smelting Co., Ltd. (VSP series, TQ-M7-VSP) was used in the same manner as above. The copper foil was placed on a smooth SUS plate with the roughened surface of the copper foil facing upward, a mold frame (the length of the frame part was 7 cm, the width was 7 cm, and the thickness was 1 mm) was placed and made to fit closely, the varnish-like composition obtained in Example 1 was poured in, and after air drying, it was further dried in a vacuum dryer at 60 °C for 3 hours or more to obtain RCC containing a copper foil and an uncured insulating adhesive layer (thickness of about 0.3 mm).

[0212] A polyimide (PI) sheet as an insulating resin layer was placed on the insulating adhesive layer side of the obtained RCC; Kapton (registered trademark) manufactured by DUPONT-TORAY Co., Ltd., with a thickness of 0.2 mm, and heat treatment was performed under the conditions of 120 °C for 30 minutes and then 200 °C for 120 minutes with a pressing pressure of about 1 MPa for hot press bonding to cure the insulating adhesive layer. After curing, a cured product of the multilayer laminate was obtained. In this multilayer cured product, the copper foil and the polyimide layer were firmly bonded via the insulating adhesive layer, and if forced to peel, material rupture occurred on the copper foil side.

[0213] (Example 8)

[0214] Fabricate Figure 2 The part corresponding to the multilayer sheet in the figure shown. As the insulating resin layer, a polyimide (PI) sheet was used; Kapton (registered trademark) manufactured by DU PONT-TORAY Co., Ltd., with a thickness of 0.2 mm. A part of the polyimide sheet from which deformation had been previously removed was closely attached to a smooth SUS plate using double-sided tape, a mold frame (the length of the frame part was 7 cm, the width was 7 cm, and the thickness was 1 mm) was placed on the sheet and made to fit closely, the varnish-like composition obtained in Example 1 was poured in, and after air drying, it was further dried in a vacuum dryer at 60 °C for 3 hours or more to obtain a multilayer sheet containing a polyimide sheet and an uncured insulating adhesive layer (thickness of about 0.3 mm).

[0215] The roughened surface of the same electrolytic copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., VSP series, TQ-M7-VSP) was placed in contact with the insulating adhesive layer side of the obtained multi-layer sheet, and heat treatment was carried out under the conditions of 120 °C for 30 minutes and then 200 °C for 120 minutes with a pressing pressure of about 1 MPa for hot pressing to cure the insulating adhesive layer. After curing, a cured product of the multi-layer laminate was obtained. In this multi-layer cured product, the copper foil and the polyimide layer were firmly bonded via the insulating adhesive layer, and if forced to peel, material rupture occurred on the copper foil side.

[0216] (Example 9)

[0217] The copper foil used was the same electrolytic copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., VSP series, TQ-M7-VSP). The copper foil was placed on a smooth SUS plate with the roughened surface of the copper foil facing up. Next, a silicon mold frame (the length of the frame part was 7 cm, the width was 7 cm, and the thickness was 0.5 mm) was placed on the roughened surface of the copper foil and made to fit closely. 700 g of toluene was further added to 300 g of the varnish-like composition obtained in Example 1. After stirring evenly, it was poured into the mold frame, air-dried, and then further dried in a vacuum dryer at 60 °C for more than 3 hours to obtain an RCC containing a copper foil and an uncured insulating adhesive layer (thickness of about 50 μm). The RCC was heat-treated under the conditions of 120 °C for 30 minutes and then 200 °C for 120 minutes with a pressing pressure of about 1 MPa to cure the insulating adhesive layer, and an RCC containing a copper foil and a cured insulating adhesive layer was obtained. Similarly to the above, this RCC was placed on a smooth SUS plate with the cured insulating adhesive layer facing up, a mold frame (the length of the frame part was 7 cm, the width was 7 cm, and the thickness was 0.5 mm) was placed on the cured insulating adhesive layer and made to fit closely. 200 g of toluene was further added to 300 g of the varnish-like composition obtained in Example 1. After stirring evenly, it was poured into the mold frame, air-dried, and then further dried in a vacuum dryer at 60 °C for more than 3 hours. The mold frame was removed to obtain an RCC containing a copper foil / cured insulating adhesive layer (about 50 μm) / insulating adhesive layer (about 100 μm) and containing a cured insulating adhesive layer. Three pieces of this RCC were overlapped and heat-treated under the conditions of 120 °C for 30 minutes and then 200 °C for 120 minutes with a pressing pressure of about 1 MPa to cure it, and a cured product of a copper foil multi-layer structure body with three insulating layers was obtained.

[0218] The cured product of the insulating adhesive layer formed from the composition of the present invention can exhibit a high gel fraction, be fully cured, and exhibit a low dielectric constant, a low dielectric loss tangent, and a low water absorption rate. In addition, a cured product having a high adhesive strength with a metal foil and an insulating resin layer can be produced from the insulating adhesive layer formed from the composition of the present invention. The cured product of the multilayer structure of the present invention has sufficient adhesive strength between the layers, and the cured product of the insulating adhesive layer contained therein exhibits a high gel fraction, excellent low dielectric properties, and a low water absorption rate. Therefore, the cured product of this multilayer structure is useful as a signal transmission line for high frequencies, an antenna, and a multilayer FCCL.

Claims

1. A multi-layer structure, characterized in that, Comprising: a metal foil having at least a part of an open surface; an insulating resin layer; and an insulating adhesive layer formed from a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer, and a monomer or polymer having a carboxyl group or an acid anhydride group, The insulating adhesive layer is joined to the insulating resin layer, and the insulating adhesive layer is joined to the surface of the metal foil opposite to the open surface.

2. The multilayer structure according to claim 1, wherein, The open surface of the metal foil is the entire surface area of the metal foil.

3. The multi-layer structure according to claim 1, wherein, The open surface of the metal foil is a part of the surface area of the metal foil, and a covering film is further provided on other parts other than this part.

4. The multilayer structure according to any one of claims 1 to 3, wherein, The open surface of the metal foil is provided for mounting of components.

5. The multilayer structure according to any one of claims 1 to 3, having any one of the following structures (1) or structure (2), Structure (1): A structure joined in the order of the metal foil, the insulating adhesive layer, and the insulating resin layer; Structure (2): A structure joined in the order of the metal foil, the insulating adhesive layer, the insulating resin layer, the insulating adhesive layer, and the metal foil.

6. The multi-layer structure according to claim 5, wherein, In the structure (1) or the structure (2), the areas of the respective layers are the same.

7. The multi-layer structure according to claim 5, wherein, In the structure (1) or the structure (2), the areas of at least a pair of the respective layers are different.

8. The multilayer structure according to any one of claims 1 to 3, wherein, The insulating resin layer contains one or more selected from the group consisting of polyimide (PI), liquid crystal polymer (LCP), polyphenylene ether (PPE), polyfunctional aromatic vinyl resin (ODV), and epoxy resin.

9. The multi-layer structure according to any one of claims 1 to 3, wherein, The olefin-aromatic vinyl compound-aromatic polyene copolymer contained in the insulating adhesive layer satisfies all of the following conditions (1) to (4), (1) The number average molecular weight of the copolymer is 500 or more and less than 100,000; (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer unit is 0 to 98% by mass or less; (3) The aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms having a plurality of vinyl groups and / or vinylidene groups in the molecule, and the content of the vinyl group and / or vinylidene group derived from the aromatic polyene unit is 2 or more and less than 20 relative to the number average molecular weight; (4) The olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, the content of the olefin monomer unit is 1% by mass or more, and the total of the olefin monomer unit, the aromatic vinyl compound monomer unit, and the aromatic polyene monomer unit is 100% by mass.

10. The multilayer structure according to any one of claims 1 to 3, wherein, The content of the monomer or polymer having a carboxyl group or an acid anhydride group contained in the insulating adhesive layer is 0.001 to 5 parts by mass with respect to 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer.

11. A cured product of a multilayer structure, which is obtained by curing the multilayer structure according to any one of claims 1 to 3.

12. A signal transmission line, antenna, or multilayer FCCL for high frequencies, comprising the cured product of the multilayer structure recited in claim 11.

13. RCC (Resin Coated Copper Foil), characterized in that, Comprising: a metal foil having an open surface in at least a part thereof; and an insulating adhesive layer formed from a composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxylic acid group or an acid anhydride group. The insulating adhesive layer is joined to the surface of the metal foil opposite to the open surface.

14. A multilayer sheet comprising an insulating adhesive layer and an insulating resin layer, the insulating adhesive layer being formed from a composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxylic acid group or an acid anhydride group, and the insulating resin layer comprising one or more selected from the group consisting of polyimide (PI), liquid crystal polymer (LCP), polyphenylene ether (PPE), polyfunctional aromatic vinyl resin (ODV), and epoxy resin.

15. RCC (Resin Coated Copper Foil), characterized in that, Comprising: a metal foil having an open surface in at least a part thereof; a cured insulating adhesive layer formed from a composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer; and an insulating adhesive layer formed from a composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer. The insulating adhesive layer is joined in the order of the metal foil / the cured insulating adhesive layer / the insulating adhesive layer to the surface of the metal foil opposite to the open surface.

16. The RCC (Resin Coated Copper Foil) according to claim 15, wherein, The composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer is a composition comprising the olefin-aromatic vinyl compound-aromatic polyene copolymer and a monomer or polymer having a carboxylic acid group or an acid anhydride group.

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