JP2023105332A - Novel crosslinker, curable composition, prepreg, laminate, metal-clad laminate and circuit board - Google Patents

Abstract

To provide a crosslinker that is suitable for a curable composition and is capable of giving a (semi)cured product having a dielectric loss tangent (Df) effectively reduced under high frequency conditions, having a sufficiently low thermal expansion coefficient (CTE), and having a sufficiently high glass transition temperature (Tg).SOLUTION: A crosslinker is represented by the formula (X) (where A is a Group 14 element selected from the group consisting of Ge, Sn, and Pb, L is a single bond, an aromatic ring, a C1-20 alkylene group, or a combination of a C1-20 alkylene group and an aromatic ring. n is an integer of 2-4. R is a hydrogen atom, a hydroxy group, or an organic group, and if R is an organic group, the atom bound to A is C).SELECTED DRAWING: Figure 1

Description

The present invention relates to novel cross-linking agents, curable compositions, prepregs, laminates, metal-clad laminates and wiring boards.

Wiring boards (also called printed wiring boards) are used for applications such as electrical equipment and electronic equipment. A wiring board can be manufactured, for example, as follows. A curable composition is impregnated into a fibrous base material and the curable composition is (semi) cured to produce a prepreg. One or more prepregs are sandwiched between a pair of metal foils, and the obtained first temporary laminate is heated and pressurized to produce a metal-clad laminate. Using the metal foil on the outermost surface of this metal-clad laminate, a conductor pattern (also referred to as a circuit pattern) such as wiring is formed. The outermost metal foil may be arranged only on one side of the first temporary laminate.

Further, one or more prepregs are superimposed on the obtained wiring board, sandwiched between a pair of metal foils, the obtained second temporary laminate is heated and pressed, and the metal foil on the outermost surface is used to A multilayer wiring board (also referred to as a multilayer printed wiring board) can be manufactured by forming a conductor pattern such as wiring. The outermost metal foil may be arranged only on one side of the second temporary laminate.

A heated and pressurized prepreg contains a fiber base material, a resin, an inorganic filler (also referred to as a filler), and the like, and is also called a composite base material. In the wiring board, the composite base material functions as an insulating layer.
The resin contained in the prepreg is a (semi-)cured product of the curable composition, and the resin contained in the composite substrate is a cured product of the curable composition.

2. Description of the Related Art In recent years, in applications such as portable electronic devices, the speed and capacity of communication have increased, and the frequency of signals has increased. A wiring board used for this purpose is required to reduce transmission loss in a high frequency region. Transmission loss includes conductor loss mainly caused by the surface resistance of the metal foil and dielectric loss caused by the dielectric loss tangent (D _f ) of the composite base material. Therefore, the resin contained in the composite base material of the wiring board used for the above application is required to reduce the dielectric loss in the high frequency region. Generally, the dielectric loss tangent (D _f ) depends on the frequency, and if the same material is used, the higher the frequency, the larger the dielectric loss tangent (D _f ) tends to be. The resin contained in the composite base material preferably has a low dielectric loss tangent (D _f ) under high frequency conditions.

If the difference in coefficient of thermal expansion (CTE) between the prepreg or composite base material and the metal foil is large, a first temporary laminate including the prepreg and the metal foil or a second temporary laminate including the composite base material, the prepreg and the metal foil will be produced. When the temporary laminate is heated and pressurized, the metal foil may be displaced or peeled off. A smaller difference in coefficient of thermal expansion (CTE) between the prepreg or composite base material and the metal foil is preferred. Since resin generally has a higher coefficient of thermal expansion (CTE) than metal foil, it is preferable that the prepreg and composite base material have a lower coefficient of thermal expansion (CTE).

A wiring board may be used in a relatively high-temperature environment. Even in this case, the resin contained in the prepreg and the composite base material preferably has a sufficiently high glass transition temperature (Tg) in order to ensure the reliability of the wiring board.

Adhesion between the composite base material and the metal foil is important in the wiring board. Conventionally, there is a technique for roughening the surface of the metal foil on the side of the composite base material in order to improve the adhesion between the composite base material and the metal foil. However, this technique is not preferable because high-frequency current loss is likely to occur.
As a technique for improving the adhesion between a composite substrate and a metal foil without roughening the surface of the metal foil on the composite substrate side, Patent Document 1 discloses a polyphenylene oxide system consisting of polyphenylene oxide and trialkenyl isocyanurate. A wiring board resin composition containing a resin and a vinylsilane such as trimethoxyvinylsilane (TMVS) and triethoxyvinylsilane (TEVS) and a wiring board obtained using the same are disclosed (claims 1 to 4). .

Japanese Patent Application Laid-Open No. 2004-259899

Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2009), 50(1). Vinylphenylmetal compounds, US3109851A. Recueil des Travaux Chimiques des Pays-Bas et de la Belgique (1960), 79, 408-12. Journal of Organometallic Chemistry (1980), 187 (3), 305-19. Inorganic Chemistry (1980), 19(4), 1089-90. Journal fuer Praktische Chemie (Leipzig) (1964), 24(1-2), 106-11. Macromolecules (2002), 35(25), 9282-9288. Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2002), 43(1), 75-76. Science of Synthesis, (2003), 5, 755-762. Journal of Organic Chemistry (2013), 78(7), 3329-3335. Journal of Photoscience (2003), 10(1), 121-126. Journal of Organometallic Chemistry (2003), 671(1-2), 113-119. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) (1990), (12), 3362-3.

Vinylsilanes such as trimethoxyvinylsilane (TMVS) and triethoxyvinylsilane (TEVS) used in Patent Document 1 are silane coupling agents containing a bond between Si and a polar oxygen atom (O).
As a result of studies by the present inventors, when a silane coupling agent containing a bond between Si and an oxygen atom (O), which is a polar atom, is added to the curable composition, the resulting composite substrate has a dielectric loss tangent (D _f ) was found to tend to increase.

The inventors have discovered that organosilicon compounds having a specific chemical structure containing two or more reactive vinyl groups and free of Si-polar atom bonds can be used as cross-linking agents in curable compositions. The composite substrate obtained by using the curable composition comprising the dielectric loss tangent (D _f ) under high frequency conditions is effectively reduced, the coefficient of thermal expansion (CTE) is sufficiently low, and the glass transition temperature (Tg) is It has been found to be sufficiently high and to have good characteristics for a wiring substrate used in a high frequency region. The present inventors have disclosed a novel organosilicon compound cross-linking agent in Japanese Patent Application No. 2021-094385 (filing date: June 4, 2021, unpublished at the time of filing of the present application).

The present inventors have also investigated Group 14 elements other than Si (specifically, Ge, Sn and Pb), and found that they contain two or more reactive vinyl groups and contain Group 14 elements and polar atoms. An organic Group 14 element compound having a specific chemical structure that does not contain a bond with can also be used as a cross-linking agent for a curable composition, and a composite substrate obtained using a curable composition containing this can be used under high frequency conditions The dielectric loss tangent (D _f ) is effectively reduced, the coefficient of thermal expansion (CTE) is sufficiently low, the glass transition temperature (Tg) is sufficiently high, and it has good characteristics for wiring substrates used in high frequency regions I found out.

Non-Patent Documents 1 to 13 report organic Group 14 element compounds in which all four atoms bonded to Ge, Sn, or Pb are nonpolar atoms and have two or more reactive vinyl groups (described later. See Tables 1 and 2). However, these documents do not report their use as a cross-linking agent. All organic Group 14 element compounds having two or more reactive vinyl groups in which all four atoms bonded to Ge, Sn or Pb are non-polar atoms are novel as cross-linking agents.

The present invention has been made in view of the above circumstances, is suitable for use in a curable composition, effectively reduces the dielectric loss tangent (D _f ) under high frequency conditions, and has a sufficiently low coefficient of thermal expansion (CTE). An object of the present invention is to provide a novel cross-linking agent capable of obtaining a (semi-) cured product having a sufficiently high glass transition temperature (Tg) and a curable composition using the same.
The novel cross-linking agent of the present invention is suitable for use in curable compositions used in applications such as prepregs, metal-clad laminates and wiring boards, but can be used in any application.

The present invention provides the following novel cross-linking agents, curable compositions, prepregs, laminates, metal-clad laminates and wiring substrates of [1] to [15].

（上式中、Ａは、Ｇｅ、ＳｎおよびＰｂからなる群より選ばれる１４族元素であり、Ｌは単結合、置換基を有していてもよい芳香環、置換基を有していてもよい炭素数１～２０のアルキレン基、または、置換基を有していてもよい炭素数１～２０のアルキレン基と置換基を有していてもよい芳香環との組合せである。ｎは２～４の整数である。Ｒは水素原子、水酸基または有機基であり、Ｒが有機基であるとき、Ａと結合した原子はＣである。） [1] A cross-linking agent represented by the following formula (X).

(In the above formula, A is a group 14 element selected from the group consisting of Ge, Sn and Pb, L is a single bond, an optionally substituted aromatic ring, a substituted an alkylene group having 1 to 20 carbon atoms, or a combination of an alkylene group having 1 to 20 carbon atoms which may have a substituent and an aromatic ring which may have a substituent, n is 2; is an integer of to 4. R is a hydrogen atom, a hydroxyl group or an organic group, and when R is an organic group, the atom bonded to A is C.)

（上式中、Ｍは、単結合または置換基を有していてもよい炭素数１～２０のアルキレン基である。ベンゼン環は置換基を有していてもよい。ベンゼン環上のビニル基の置換位置は任意である。ｎは２～４の整数である。Ｒは水素原子、水酸基または有機基であり、Ｒが有機基であるとき、Ａと結合した原子はＣである。） [2] The cross-linking agent of [1] represented by the following formula (1).

(In the above formula, M is a single bond or an optionally substituted alkylene group having 1 to 20 carbon atoms. The benzene ring may have a substituent. A vinyl group on the benzene ring is any position, n is an integer of 2 to 4. R is a hydrogen atom, a hydroxyl group or an organic group, and when R is an organic group, the atom bonded to A is C.)

[3] The cross-linking agent of [1] or [2], wherein A is Ge.
[4] The cross-linking agent according to any one of [1] to [3], wherein R is an optionally substituted alkyl group having 1 to 18 carbon atoms.
[5] The cross-linking agent of [2], wherein M is a single bond or an alkylene group having 1 to 4 carbon atoms.
[6] The cross-linking agent of [2], wherein A is Ge, R is a methyl group, n is 2, and the substitution position of the vinyl group on the benzene ring is the ortho position.
[7] The cross-linking agent of [2], wherein the substituted position of the vinyl group on the benzene ring is the meta position.
[8] The cross-linking agent according to any one of [1] to [7], which is for a curable composition used for producing prepregs, metal-clad laminates or wiring boards.

[9] A curable composition comprising the cross-linking agent of any one of [1] to [8] and a curable compound having two or more cross-linkable functional groups capable of cross-linking with the cross-linking agent.
[10] A prepreg comprising a fiber base material and a semi-cured or cured product of the curable composition of [9].
[11] A laminate comprising a substrate and a curable composition layer comprising the curable composition of [9].
[12] A laminate comprising a substrate and a semi-cured product of the curable composition of [9] or a (semi-)cured product-containing layer containing the cured product.
[13] The laminate of [11] or [12], wherein the substrate is a resin film or metal foil.
[14] A metal-clad laminate comprising an insulating layer containing a cured product of the curable composition of [9] and a metal foil.
[15] A wiring substrate comprising an insulating layer containing a cured product of the curable composition of [9] and wiring.

According to the present invention, it is suitable for use in a curable composition, the dielectric loss tangent (D _f ) under high frequency conditions is effectively reduced, the coefficient of thermal expansion (CTE) is sufficiently low, and the glass transition temperature (Tg) is A novel cross-linking agent capable of obtaining a sufficiently high (semi-) cured product and a curable composition using the same can be provided.

1 is a schematic cross-sectional view of a metal-clad laminate of a first embodiment according to the present invention; FIG. FIG. 2 is a schematic cross-sectional view of a metal-clad laminate of a second embodiment according to the present invention; 1 is a schematic cross-sectional view of a wiring board according to one embodiment of the present invention; FIG.

As used herein, (semi-)curing is a generic term for semi-curing and curing.
In this specification, unless otherwise specified, the term "wiring board" includes a multilayer wiring board.
In this specification, "high frequency region" is defined as a region with a frequency of 1 GHz or higher.
In the present specification, unless otherwise specified, "number average molecular weight (Mn)" is a polystyrene equivalent number average molecular weight determined by a gel permeation chromatography (GPC) method.
In this specification, unless otherwise specified, the numerical range "to" is used to include the numerical values before and after it as lower and upper limits.
Embodiments of the present invention will be described below.

（上式中、Ａは、Ｇｅ、ＳｎおよびＰｂからなる群より選ばれる１４族元素であり、Ｌは単結合、置換基を有していてもよい芳香環、置換基を有していてもよい炭素数１～２０のアルキレン基、または、置換基を有していてもよい炭素数１～２０のアルキレン基と置換基を有していてもよい芳香環との組合せである。ｎは２～４の整数である。Ｒは水素原子、水酸基または有機基であり、Ｒが有機基であるとき、Ａと結合した原子はＣである。） [New cross-linking agent]
The cross-linking agent of the present invention is represented by the following formula (X).

(In the above formula, A is a group 14 element selected from the group consisting of Ge, Sn and Pb, L is a single bond, an optionally substituted aromatic ring, a substituted an alkylene group having 1 to 20 carbon atoms, or a combination of an alkylene group having 1 to 20 carbon atoms which may have a substituent and an aromatic ring which may have a substituent, n is 2; is an integer of to 4. R is a hydrogen atom, a hydroxyl group or an organic group, and when R is an organic group, the atom bonded to A is C.)

（上式中、Ｍは、単結合または置換基を有していてもよい炭素数１～２０のアルキレン基である。ベンゼン環は置換基を有していてもよい。ベンゼン環上のビニル基の置換位置は任意である。ｎは２～４の整数である。Ｒは水素原子、水酸基または有機基であり、Ｒが有機基であるとき、Ａと結合した原子はＣである。） The cross-linking agent of the present invention is preferably represented by the following formula (1).

(In the above formula, M is a single bond or an optionally substituted alkylene group having 1 to 20 carbon atoms. The benzene ring may have a substituent. A vinyl group on the benzene ring is any position, n is an integer of 2 to 4. R is a hydrogen atom, a hydroxyl group or an organic group, and when R is an organic group, the atom bonded to A is C.)

The cross-linking agent of the present invention can be used for any purpose and is suitable for curable compositions, prepregs, laminates, metal-clad laminates, wiring boards and the like.

[Curable composition]
The curable composition of the present invention comprises the cross-linking agent of the present invention and a curable compound having two or more cross-linkable functional groups capable of cross-linking with this cross-linking agent.
The curable composition may be thermosetting or active energy ray curable. An active energy ray-curable composition is a composition that is cured by irradiation with active energy rays such as ultraviolet rays and electron beams. Thermosetting is preferred for applications such as metal-clad laminates and wiring boards.

Curable compounds include monomers, oligomers, prepolymers, and the like. One or more of these can be used.
Cured products of curable compounds include polyphenylene ether resins (PPE), bismaleimide resins, epoxy resins, fluorine resins, polyimide resins, olefin resins, polyester resins, polystyrene resins, hydrocarbon elastomers, benzoxazine resins, and active ester resins. , cyanate ester resins, butadiene resins, hydrogenated or non-hydrogenated styrene-butadiene resins, vinyl resins, cycloolefin polymers, aromatic polymers, divinyl aromatic polymers and combinations thereof.

For applications such as metal-clad laminates and wiring boards, the cured product of the curable compound preferably contains polyphenylene ether resin (PPE).
As used herein, "polyphenylene ether resin (PPE)" is intended to include unmodified polyphenylene ether resins and modified polyphenylene ether resins, unless otherwise specified.

In the above applications, the curable compound is preferably, for example, a polyphenylene ether oligomer represented by the following formula (P).

X at both ends of formula (P) is each independently a group represented by the following formula (x1) or the following formula (x2). In these formulas, "*" indicates a bond with an oxygen atom.

m is preferably 1-20, more preferably 3-15.
n is preferably 1-20, more preferably 3-15.

The (semi-)cured product of the curable composition contains the reaction product of the curable compound and the cross-linking agent of the present invention.

The number average molecular weight (Mn) of the oligomer is not particularly limited, preferably 1000-5000, more preferably 1000-4000.

Preferably, the curable composition comprises one or more polymerization initiators. As the polymerization initiator, organic peroxides, azo compounds, other known polymerization initiators, and combinations thereof can be used. Specific examples include dicumyl peroxide, benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butyl peroxy)hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, α,α'-di(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di( t-butylperoxy)hexane, di-t-butylperoxyisophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy ) octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, trimethylsilyltriphenylsilylperoxide and azobisisobutyronitrile.

The curable composition may optionally contain one or more additives. Examples of additives include inorganic fillers (also referred to as fillers), compatibilizers and flame retardants.
Examples of inorganic fillers include silica such as spherical silica, alumina, metal oxides such as titanium oxide and mica; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; talc; aluminum borate; barium sulfate; Calcium etc. are mentioned. One or more of these can be used. Among them, silica, mica and talc are preferred, and spherical silica is more preferred, from the viewpoint of low thermal expansion.
The inorganic filler may be surface treated with an epoxysilane-type, vinylsilane-type, methacrylsilane-type, or aminosilane-type silane coupling agent. The timing of surface treatment with a silane coupling agent is not particularly limited. An inorganic filler surface-treated with a silane coupling agent may be prepared in advance, or the silane coupling agent may be added by an integral blend method during preparation of the curable composition.

Examples of flame retardants include halogen-based flame retardants and phosphorus-based flame retardants. One or more of these can be used. Examples of halogen-based flame retardants include brominated flame retardants such as pentabromodiphenyl ether, octabromodiphenyl ether, decabromodiphenyl ether, tetrabromobisphenol A and hexabromocyclododecane; and chlorine-based flame retardants such as chlorinated paraffin. . Examples of phosphorus-based flame retardants include phosphoric acid esters such as condensed phosphoric acid esters and cyclic phosphoric acid esters; phosphazene compounds such as cyclic phosphazene compounds; phosphinate-based flame retardants such as aluminum dialkylphosphinate; melamine-based flame retardants such as melamine polyphosphate; and phosphine oxide compounds having a diphenylphosphine oxide group.

The curable composition can optionally contain one or more organic solvents. The organic solvent is not particularly limited, and includes ketones such as methyl ethyl ketone; ethers such as dibutyl ether; esters such as ethyl acetate; amides such as dimethylformamide; aromatic hydrocarbons such as benzene, toluene and xylene; and chlorinated hydrocarbons such as

In the curable composition, the solid content concentration and composition can be designed according to the application.
For applications such as prepreg, the solid content concentration is preferably 50 to 90% by mass.

[Prepreg]
The prepreg of the present invention includes a fiber base material and a (semi-)cured product of the curable composition of the present invention. The (semi-)cured product may contain additives such as an inorganic filler (filler), if necessary.
A prepreg can be produced by impregnating a fiber base material with a curable composition and (semi-)curing it by heat curing or the like.

Materials for the fiber base material are not particularly limited, and include inorganic fibers such as glass fibers, silica fibers and carbon fibers; organic fibers such as aramid fibers and polyester fibers; and combinations thereof. For applications such as metal-clad laminates and wiring boards, glass fiber and the like are preferred. Examples of the form of the glass fiber substrate include glass cloth, glass paper and glass mat.

The curing conditions of the curable composition can be set according to the composition of the curable composition, and semi-curing conditions (conditions under which complete curing is not performed) are preferred.
When using a curable composition containing a polyphenylene ether oligomer represented by the above formula (P), for example, heat curing by heating at 80 to 180° C. for 1 to 10 minutes is preferred.
In applications such as metal-clad laminates and wiring boards, it is preferable to adjust the composition and curing conditions of the curable composition so that the resin content in the resulting prepreg is within the range of 40 to 80% by mass.

[Laminate]
A first laminate of the present invention includes a substrate and a curable composition layer comprising the curable composition of the present invention.
The second laminate of the present invention includes a base material and a (semi-)cured product-containing layer containing a (semi-)cured product of the curable composition of the present invention.
In the first and second laminates of the present invention, the base material is not particularly limited, and includes resin films, metal foils, combinations thereof, and the like.
The (semi-)cured product-containing layer may be a layer containing a fiber base material and a (semi-)cured product of the curable composition of the present invention.
The resin film is not particularly limited, and known films can be used. Constituent resins of the resin film include polyimide, polyethylene terephthalate (PET), polyethylene naphthalate, cycloolefin polymer and polyether sulfide.
As the metal foil, copper foil, silver foil, gold foil, aluminum foil, combinations thereof, and the like are preferable, and copper foil and the like are more preferable, because of their low electrical resistance.

[Metal clad laminate]
The metal-clad laminate of the present invention includes an insulating layer containing a cured product of the curable composition of the present invention and a metal foil.
The insulating layer may be a layer containing a fiber base material and a cured product of the curable composition of the present invention.
As the metal foil, copper foil, silver foil, gold foil, aluminum foil, combinations thereof, and the like are preferable, and copper foil and the like are more preferable, because of their low electrical resistance. The metal foil may have a metal plating layer on its surface. The metal foil may be a metal foil with a carrier that includes an ultra-thin metal foil and a carrier metal foil that supports it. At least one surface of the metal foil may be subjected to surface treatment such as rust prevention treatment, silane treatment, surface roughening treatment and barrier forming treatment.
The thickness of the metal foil is not particularly limited, and is suitable for forming a conductor pattern (also called a circuit pattern) such as wiring. is 1.0 to 40 μm.

The metal-clad laminate may be a single-sided metal-clad laminate having metal foil on one side, or a double-sided metal-clad laminate having metal foil on both sides, and may be a double-sided metal-clad laminate. preferable.
A single-sided metal-clad laminate can be produced by stacking one or more of the above prepregs and a metal foil, and heating and pressurizing the resulting first temporary laminate.
A double-sided metal-clad laminate can be produced by sandwiching one or more of the above prepregs between a pair of metal foils and heating and pressurizing the obtained first temporary laminate.
A metal clad laminate using copper foil as the metal foil is called a copper clad laminate (CCL).

The insulating layer preferably consists of a heat-pressed prepreg. The heat-pressed prepreg contains a fiber base material and a resin, and can optionally contain one or more additives such as inorganic fillers and flame retardants. A heat-pressed prepreg is also called a composite base material.
The heating and pressurizing conditions for the first temporary laminate are not particularly limited, and are preferably, for example, a temperature of 170 to 250° C., a pressure of 0.3 to 30 MPa, and a time of 3 to 240 minutes.

1 and 2 show schematic cross-sectional views of metal-clad laminates of first and second embodiments according to the present invention.
The metal-clad laminate 1 shown in FIG. 1 is made of a prepreg heated and pressed, and a metal foil (metal It is a single-sided metal-clad laminate (laminate) in which layers) 12 are laminated.
The metal-clad laminate 2 shown in FIG. 2 is made of a prepreg heated and pressed, and a metal foil (metal Layer) 12 is a double-sided metal-clad laminate laminated.

The metal-clad laminates 1 and 2 may have layers other than those described above.
The metal-clad laminates 1 and 2 may have an adhesive layer between the composite base material (cured material-containing layer) 11 and the metal foil (metal layer) 12 in order to enhance their adhesion. Known materials can be used for the adhesive layer, and examples thereof include epoxy resins, cyanate ester resins, acrylic resins, polyimide resins, maleimide resins, adhesive fluororesins, and combinations thereof. Commercially available adhesive fluororesins include "Fluon LM-ETFE LH-8000", "AH-5000", "AH-2000" and "EA-2000" manufactured by AGC.

The thickness of the composite base material can be appropriately designed according to the application. From the viewpoint of preventing disconnection of the wiring board, the thickness is preferably 50 μm or more, more preferably 70 μm or more, and particularly preferably 100 μm or more. From the viewpoint of flexibility, miniaturization and weight reduction of the wiring board, the thickness is preferably 300 μm or less, more preferably 250 μm or less, and particularly preferably 200 μm or less.

[Wiring board]
The wiring board of the present invention includes an insulating layer containing a cured product of the curable composition of the present invention, and wiring.
The wiring board can be produced by forming a conductor pattern (circuit pattern) such as wiring using the metal foil on the outermost surface of the metal-clad laminate of the present invention. Methods for forming conductor patterns such as wiring include the subtractive method, in which wiring is formed by etching metal foil, and the MSAP (Modified Semi-Additive Process) method, in which wiring is formed by plating on metal foil. mentioned.

FIG. 3 shows a schematic cross-sectional view of a wiring board according to one embodiment of the present invention. The wiring board 3 shown in FIG. 3 is formed by using the metal foil 12 on at least one of the outermost surfaces of the metal-clad laminate 2 of the second embodiment shown in FIG. is formed.
The wiring board 3 is made of a prepreg heated and pressed, and a conductor pattern such as a wiring 22W is provided on at least one side of a composite base material (cured product-containing layer, insulating layer) 11 containing a cured product of the curable composition of the present invention. A (circuit pattern) 22 is formed.

Further, one or more prepregs are superimposed on the obtained wiring board, sandwiched between a pair of metal foils, the obtained second temporary laminate is heated and pressed, and wiring is performed using the outermost metal foil. A multilayer wiring board (also referred to as a multilayer printed wiring board) may be manufactured by forming a conductor pattern such as the above. The outermost metal foil may be arranged only on one side of the temporary laminate.
The wiring board of the present invention is suitable for use in a high frequency range (frequency range of 10 GHz or higher).

2. Description of the Related Art In recent years, in applications such as portable electronic devices, the speed and capacity of communication have increased, and the frequency of signals has increased. A wiring board used for this purpose is required to reduce transmission loss in a high frequency region. Therefore, the resin contained in the composite base material of the wiring board used for the above application is required to reduce the dielectric loss in the high frequency region. Generally, the dielectric loss tangent (D _f ) depends on the frequency, and if the same material is used, the higher the frequency, the larger the dielectric loss tangent (D _f ) tends to be. The resin contained in the composite base material preferably has a low dielectric loss tangent (D _f ) under high frequency conditions.

If the difference in coefficient of thermal expansion (CTE) between the prepreg or composite base material and the metal foil is large, a first temporary laminate including the prepreg and the metal foil or a second temporary laminate including the composite base material, the prepreg and the metal foil will be produced. When the temporary laminate is heated and pressurized, the metal foil may be displaced or peeled off. A smaller difference in coefficient of thermal expansion (CTE) between the prepreg or composite base material and the metal foil is preferred. Since resin generally has a higher coefficient of thermal expansion (CTE) than metal foil, it is preferable that the prepreg and composite base material have a lower coefficient of thermal expansion (CTE).

A wiring board may be used in a relatively high-temperature environment. Even in this case, the resin contained in the prepreg and the composite base material preferably has a sufficiently high glass transition temperature (Tg) in order to ensure the reliability of the wiring board.

In the cross-linking agent of the present invention, unlike the silane coupling agent used in Patent Document 1 mentioned in the Background Art section, all four atoms bonded to Group 14 elements are nonpolar atoms (specifically is a hydrogen atom or a carbon atom).
As a result of studies by the present inventors, when an organic Group 14 element compound represented by Formula (X), preferably Formula (1), is added to the curable composition, the organic Group 14 element compound has two It was found that it functions as a cross-linking agent for cross-linking the curable compound having the cross-linkable functional group and can effectively reduce the dielectric loss tangent (D _f ) of the (semi-)cured product of the curable composition.
In addition, the (semi-)cured product of the curable composition containing the organic group 14 element compound represented by formula (X), preferably formula (1), as a cross-linking agent has a sufficiently low coefficient of thermal expansion (CTE), It was found that the glass transition temperature (Tg) was sufficiently high.
In addition, the (semi) cured product of the curable composition containing the organic Group 14 element compound represented by the formula (X), preferably the formula (1), as a cross-linking agent has practical adhesion to metals such as copper foil. found to be generally good.

By adding an organic group 14 element compound represented by formula (X), preferably formula (1), to the curable composition as a cross-linking agent, the dielectric loss tangent (D _f ) under high frequency conditions is effectively reduced. , a (semi-)cured product having a sufficiently low coefficient of thermal expansion (CTE) and a sufficiently high glass transition temperature (Tg) can be obtained. This (semi-)cured product is suitable for a composite base material, an insulating layer, and the like suitable for a wiring substrate used in a high frequency region.

The (semi-)cured product of the curable composition of the present invention and the composite substrate containing the same preferably have a dielectric loss tangent (D _f ) under high-frequency conditions, for example, within the following range.
A smaller dielectric loss tangent (D _f ) at a frequency of 10 GHz is preferable, and is preferably 0.01 or less, more preferably 0.005 or less, and particularly preferably 0.003 or less. The lower limit is not particularly limited, and is, for example, 0.0001.

The coefficient of thermal expansion (CTE) of the (semi-)cured product of the curable composition of the present invention and the composite substrate containing the same is preferably, for example, within the following range.
The coefficient of thermal expansion (CTE) is preferably as small as possible, preferably 70 ppm/°C or less, more preferably 60 ppm/°C or less, particularly preferably 50 ppm/°C or less, and most preferably 40 ppm/°C or less. The lower limit is not particularly limited, and is, for example, 1 ppm/°C.

The glass transition temperature (Tg) of the (semi-)cured product of the curable composition of the present invention is preferably 150° C. or higher, more preferably 180° C. or higher, and particularly preferably 200° C. or higher. The upper limit is not particularly limited, and is 300° C., for example.

The dielectric loss tangent (D _f ), coefficient of thermal expansion (CTE) and glass transition temperature (Tg) can be measured by the methods described in the section [Examples] below.

In the organic group 14 element compound represented by formula (1), the benzene ring may have a substituent. Examples of substituents that the benzene ring may have include alkyl groups and aryl groups having 1 to 18 carbon atoms, and from the viewpoint of raw material availability, methyl group, ethyl group, propyl group, butyl group, hexyl , octyl, phenyl and tolyl groups are preferred. The benzene ring preferably has no substituents.

In the organic Group 14 element compound represented by the formula (1), the vinyl group-substituted position on the benzene ring may be ortho, meta or para positions, and any of them may be used. In the organic group 14 element compound represented by formula (1), all the compounds in which the substitution position is the meta position are novel compounds.

In the organic group 14 element compound represented by formula (1), the number of reactive functional groups (also referred to simply as the number of functional groups) n is 2-4.

In the organic group 14 element compound represented by formula (1), R is a hydrogen atom, a hydroxyl group or an organic group, preferably an optionally substituted alkyl group having 1 to 18 carbon atoms. R preferably does not contain a polar atom such as an oxygen atom (O), since the dielectric loss tangent (D _f ) of the (semi-)cured product of the curable composition can be more effectively reduced under high frequency conditions. R is preferably an unsubstituted alkyl group having 1 to 18 carbon atoms. More preferably, it is a straight-chain alkyl group having 1 to 18 carbon atoms. For example, a methyl group etc. are mentioned.
The higher the carbon number of R, the lower the polarity of the crosslinked structure, and the dielectric loss tangent (D _f ) of the (semi-) cured product of the curable composition under high frequency conditions. It may be possible to reduce more effectively. . From the viewpoint of ease of synthesis, the upper limit of the number of carbon atoms is 18. From the viewpoint of the effect of reducing the dielectric loss tangent (D _f ) of the (semi-)cured product of the curable composition under high frequency conditions and the ease of synthesis, the number of carbon atoms in R is more preferably 3 to 18, particularly preferably 8 to 8. is 18.
Preferred aspects of R in the organic Group 14 element compound represented by Formula (X) are the same as those of R in the organic Group 14 element compound represented by Formula (1).

In the organic group 14 element compound represented by formula (1), M is a single bond or an optionally substituted alkylene group having 1 to 20 carbon atoms. The upper limit of the number of carbon atoms is 20 from the viewpoint of ease of synthesis. From the viewpoint of ease of synthesizing the organic group 14 element compound, M is preferably a single bond or an alkylene group having 1 to 4 carbon atoms, more preferably a single bond or a methylene group.

The organic group 14 element compound represented by formula (X), preferably formula (1), can be synthesized by applying a known synthesis method. For specific synthesis examples, see the section "Examples".
For example, in the [Examples] section, the present inventors have described the formula ( An organic Group 14 element compound represented by 1) was synthesized.

Examples of the organic group 14 element compound represented by formula (1) include o-, m-, and p-compounds listed in Tables 1 and 2. The compounds shown in Table 1 are polyvinylphenyl compounds in which M is a single bond, and the compounds shown in Table 2 are polyvinylbenzyl compounds in which M is a methylene group.
In Tables 1 and 2, some compounds are reported in Non-Patent Documents 1-13. However, Non-Patent Documents 1 to 13 do not describe or suggest the use of organic Group 14 element compounds as cross-linking agents, nor do they describe their dielectric properties. All organic Group 14 element compounds having two or more reactive vinyl groups in which all four atoms bonded to Ge, Sn or Pb are non-polar atoms are novel as cross-linking agents.
Some of the compounds listed in Tables 1 and 2 are novel compounds. For example, all of the m-compounds listed in Tables 1 and 2 are novel compounds.
Compounds not shown in Tables 1 and 2 among the organic group 14 element compounds represented by formula (1) are also novel compounds.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is suitable for use in a curable composition, effectively reduces the dielectric loss tangent (D _f ) under high frequency conditions, has a sufficiently low coefficient of thermal expansion (CTE), and provides glass. A novel cross-linking agent capable of obtaining a (semi-) cured product having a sufficiently high transition temperature (Tg) and a curable composition using the same can be provided.
The novel cross-linking agent of the present invention is suitable for use in curable compositions used in applications such as prepregs, metal-clad laminates and wiring boards, but can be used in any application.

[Use]
The novel organic Group 14 element compound of the present invention is suitable as a cross-linking agent and the like.
The crosslinkers of the present invention are suitable for curable compositions containing curable compounds such as monomers, oligomers and prepolymers.
The novel organic Group 14 element compound and the novel cross-linking agent of the present invention are suitable for curable compositions used in applications such as prepregs, metal-clad laminates and wiring boards.
The curable composition containing the cross-linking agent of the present invention is suitable for use in applications such as prepregs, metal-clad laminates and wiring boards.
INDUSTRIAL APPLICABILITY The metal-clad laminate of the present invention is suitable for wiring substrates and the like used in various electric devices and various electronic devices.
The wiring board of the present invention is suitable for use in portable electronic devices such as mobile phones, smart phones, personal digital assistants and notebook computers; antennas for mobile phone base stations and automobiles; electronic devices such as servers, routers and backplanes; Radar for prevention, various sensors (for example, automotive sensors such as engine management sensors), and the like.
The wiring board of the present invention is particularly suitable for communication using high-frequency signals, and is suitable for various applications requiring reduction of transmission loss in a high-frequency region.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. Example 1 is an example, and Examples 21 and 22 are comparative examples. Unless otherwise specified, room temperature is around 25°C.

[Commercial reagent]
Unless otherwise specified, commercially available catalysts and reagents were used as they were in the [Examples] section. Dehydrated and deoxygenated commercial products were used as solvents.

[Evaluation items and evaluation methods of organic Group 14 element compounds]
(structure)
The structure of the synthesized organic Group 14 element compound was identified by ¹ H-NMR measurement using a nuclear magnetic resonance apparatus (“AVANCE NEO400” manufactured by Bruker).

[Method for preparing evaluation sample (film-like cured product)]
As a curable compound, the following polyphenylene ether oligomer was prepared.
(SA9000) Bifunctional methacrylic-modified PPE ("SA9000" manufactured by SABIC).

SA9000 is represented by the following formula.

The above bifunctional methacrylic-modified PPE (SA9000), the organic Group 14 element compound synthesized or prepared in each example, dicumyl peroxide as a radical polymerization initiator, and toluene were mixed in a mass ratio of 7:3:0. A toluene solution (curable composition) was prepared by mixing at 1:7 and stirring at room temperature.
Next, using an applicator (manufactured by Yoshimitsu Seiki Co., Ltd.), the toluene solution was applied onto a polyimide film having a thickness of 125 μm to form a coating film having a thickness of 250 μm.
After drying by heating at 80° C. for 30 minutes in an oven in an air atmosphere, the coating film is thermally cured (thermal cross-linking reaction) by heating at 200° C. for 2 hours in a nitrogen atmosphere to obtain a thickness of about 100 μm. A sample for evaluation (film-like cured product) was obtained. The evaluation samples obtained were evaluated as follows.

[Evaluation items and evaluation methods of film-like cured product]
(Relative permittivity (D _k ) and dissipation factor (D _f ))
The dielectric constant (D _k ) and dielectric loss tangent (D _f ) of the evaluation sample (cured film) at 10 GHz are measured at room temperature by the SPDR method using a vector network analyzer (“E8361C” manufactured by Agilent Technologies). bottom.

(Glass transition temperature Tg)
Using a dynamic viscoelasticity measuring device (“DVA-200” manufactured by IT Keisoku Co., Ltd.), dynamic viscoelasticity measurement (DMA) of the evaluation sample (film-like cured product) was performed, and the glass transition temperature (Tg ) (°C) was measured. The measurement was performed under the conditions of a frequency of 10 Hz, a heating rate of 2°C/min, and a temperature range of 25 to 300°C.

(Coefficient of thermal expansion (CTE))
Using a thermomechanical analyzer ("TMA/SS7100" manufactured by SII Nanotechnology Co., Ltd.), the thermal expansion coefficient (CTE) of the evaluation sample (film-like cured product) below the glass transition temperature (Tg) was measured. . The measurement was carried out under the conditions of a temperature increase rate of 5°C/min and a temperature range of -50 to 340°C.

[Example 1] Synthesis of bis(2-vinylphenyl)germane Under a nitrogen atmosphere, 2-bromostyrene (6.68 g, 34.7 mmol) and tetrahydrofuran (THF, 84 mL) were charged in a 300 mL four-necked flask. . This solution was cooled to −70° C. or lower, and n-BuLi/n-hexane solution (1.6 mol/L, 21.4 mL, 34.2 mmol) was added dropwise thereto over 30 minutes. C. or below and stirred for 1 hour. Dimethylgermanium dichloride (1.99 mL, 16.6 mmol) was added dropwise to the resulting reaction solution over 30 minutes, and the mixture was stirred at the same temperature as above for 1 hour. The flask was warmed to room temperature and stirred for 1 hour. The reaction mixture was quenched with saturated aqueous ammonium chloride (60 mL), stirred at room temperature for 1 hour and the organic phase separated. Furthermore, diethyl ether (60 mL) was added to the aqueous phase and extraction was performed twice to separate the organic phase. The organic phases from these extractions were combined. The combined organic phase was dried with magnesium sulfate, filtered, and the filtrate was concentrated under vacuum to give crude material. The crude product was purified by silica gel column chromatography (mobile phase: n-hexane) to obtain 4.14 g of colorless solid bis(2-vinylphenyl)germane (yield: 82%).
The reaction scheme and NMR analysis results are as follows.

¹H-NMR (CDCl₃) : δ (ppm) 7.57 (ddm, 2H, J=0.60, 7.87 Hz, Ar-H), 7.43 (dd, 2H, J=0.95, 7.39 Hz, Ar-H), 7.35 (ddd, 2H, J=0.83, 7.27, 8.70 Hz, Ar-H), 7.23 (ddd, 2H, J=1.31, 7.39, 8.58 Hz, Ar-H), 6.80 (dd, 2H, J=10.85, 17.17 Hz, -CH=CH₂), 5.59 (dd, 1H, J=1.19, 10.85 Hz, -CH=CH₂), 5.13 (dd, 1H, J=1.19, 17.17 Hz, -CH=CH₂), 0.71 (s, 6H, Ge-CH₃).

¹ H-NMR (CDCl ₃ ): δ (ppm) 7.57 (ddm, 2H, J=0.60, 7.87 Hz, Ar-H), 7.43 (dd, 2H, J=0.95, 7.39 Hz, Ar-H), 7.35 (ddd, 2H, J=0.83, 7.27, 8.70 Hz, Ar-H), 7.23 (ddd, 2H, J=1.31, 7.39, 8.58 Hz, Ar-H), 6.80 (dd, 2H, J=10.85, 17.17 Hz, -CH= _CH2 ), 5.59 (dd, 1H, J=1.19, 10.85 Hz, -CH=CH2), 5.13 (dd, 1H, J=1.19, 17.17 Hz, -CH _{=CH2 )} , 0.71 (s, 6H, Ge- _CH3 ).

[Example 21]
As a comparative organic group 14 element compound, trimethoxyvinylsilane (TMVS, product of TCI), which is a commercially available silane coupling agent, was prepared.

[Example 22]
As a comparative organic Group 14 element compound, triethoxyvinylsilane (TEVS, product of TCI), which is a commercially available silane coupling agent, was prepared.

[Evaluation and results]
In Examples 1, 21, and 22, using the organic group 14 element compound obtained or prepared, an evaluation sample was prepared and evaluated according to the above [Method for preparing evaluation sample (film-like cured product)]. Table 3 shows the evaluation results.

[Summary of results]
In Example 1, an organic group 14 element compound represented by formula (1) was used as a cross-linking agent to obtain a film-like cured product.
In Examples 21 and 22, a film-like cured product was obtained using a silane coupling agent, which is an organic Group 14 element compound for comparison.
From the comparison between Example 1 and Examples 21 and 22, it is found that the dielectric loss tangent (D _f ) under high frequency conditions can be effectively reduced by using the organic group 14 element compound represented by the formula (1) as the cross-linking agent. rice field.
In Example 1, the dielectric loss tangent (D _f ) under high frequency conditions is effectively reduced, and a cured film having a sufficiently low coefficient of thermal expansion (CTE) and a sufficiently high glass transition temperature (Tg) can be obtained. rice field.

[Example 101]
A bifunctional methacrylic-modified PPE (SA9000), the organic Group 14 element compound synthesized in Example 1, dicumyl peroxide as a radical polymerization initiator, spherical silica as an inorganic filler, and toluene were combined at a mass ratio of 7. :3:0.1:10:10 and stirred at room temperature to prepare a curable composition (varnish).
After impregnating a glass cloth (E glass, #2116) as a fiber base material with the obtained curable composition (varnish), the curable composition is semi-cured by heating at 130 ° C. for 5 minutes, Got the prepreg.
Two sheets of the obtained prepreg were laminated, sandwiched between a pair of copper foils, and the resulting temporary laminate was heated and pressed under conditions of 200° C., 1.5 hours, and 3 MPa to produce a metal-clad laminate. .

The present invention is not limited to the above-described embodiments and examples, and design changes can be made as appropriate without departing from the gist of the present invention.

1, 2: Metal-clad laminate, 3: Wiring board, 11: Composite base material, 12: Metal foil, 22: Conductor pattern (circuit pattern), 22W: Wiring.

Claims (15)

A cross-linking agent represented by the following formula (X).

(In the above formula, A is a group 14 element selected from the group consisting of Ge, Sn and Pb, L is a single bond, an optionally substituted aromatic ring, a substituted an alkylene group having 1 to 20 carbon atoms, or a combination of an alkylene group having 1 to 20 carbon atoms which may have a substituent and an aromatic ring which may have a substituent, n is 2; is an integer of to 4. R is a hydrogen atom, a hydroxyl group or an organic group, and when R is an organic group, the atom bonded to A is C.) The cross-linking agent according to claim 1, represented by the following formula (1).

(In the above formula, M is a single bond or an optionally substituted alkylene group having 1 to 20 carbon atoms. The benzene ring may have a substituent. A vinyl group on the benzene ring is any position, n is an integer of 2 to 4. R is a hydrogen atom, a hydroxyl group or an organic group, and when R is an organic group, the atom bonded to A is C.) 3. The cross-linking agent according to claim 1 or 2, wherein A is Ge. The cross-linking agent according to any one of claims 1 to 3, wherein R is an optionally substituted alkyl group having 1 to 18 carbon atoms. 3. The cross-linking agent according to claim 2, wherein M is a single bond or an alkylene group having 1 to 4 carbon atoms. 3. The cross-linking agent according to claim 2, wherein A is Ge, R is a methyl group, n is 2, and the substitution position of the vinyl group on the benzene ring is the ortho position. 3. The cross-linking agent according to claim 2, wherein the substitution position of the vinyl group on the benzene ring is the meta position. The cross-linking agent according to any one of claims 1 to 7, which is used for curable compositions used in the production of prepregs, metal-clad laminates or wiring boards. A curable composition comprising the cross-linking agent according to any one of claims 1 to 8 and a curable compound having two or more cross-linkable functional groups capable of cross-linking with the cross-linking agent. A prepreg comprising a fiber base material and a semi-cured or cured product of the curable composition according to claim 9. A laminate comprising a substrate and a curable composition layer comprising the curable composition according to claim 9 . A laminate comprising a substrate and a semi-cured product of the curable composition according to claim 9 or a (semi-)cured product-containing layer containing the cured product. The laminate according to claim 11 or 12, wherein the base material is a resin film or metal foil. A metal-clad laminate comprising an insulating layer containing a cured product of the curable composition according to claim 9 and a metal foil. A wiring substrate comprising an insulating layer containing a cured product of the curable composition according to claim 9 and wiring.

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