Multilayer body and production method for printed wiring board

Abstract

Provided are a multilayer body and a production method for a printed wiring board. A multilayer body according to the present invention includes a metal foil that has a surface roughness Rz of no more than 2 μm as measured in accordance with JIS B0601 1994 at at least one surface and a layer that contains a resin composition and is provided on a surface of the metal foil that has a surface roughness Rz of no more than 2 μm. The resin composition includes a thermosetting compound and a compound that has an unshared electron pair, includes an aromatic ring, and has a melting point of at least 10°C. The thermosetting compound may also have an unshared electron pair.

Description

Multilayer body and method for manufacturing printed wiring board

[0001] The present invention relates to a method for manufacturing a multilayer body and a printed wiring board, and more particularly to a method for manufacturing a multilayer body and a printed wiring board that are capable of forming a fine wiring pattern.

[0002] In recent years, as electronic devices have become smaller, thinner, and lighter, the demand for higher density printed wiring boards has been increasing, necessitating the formation of fine wiring patterns (circuits). Conventional circuit formation methods include the subtractive method, in which circuits are formed by etching metal foil, and the (semi-)additive method, in which a conductor layer is formed on an insulating layer by plating. However, the subtractive method uses metal foil with a pronounced uneven matte surface that provides good adhesion to the insulating layer. During circuit formation, the unevenness of the matte surface of the metal foil tends to leave some of the protrusions on the resin surface of the laminate. To completely remove these, extending the etching time can result in over-etching of the circuit, resulting in reduced circuit positional accuracy and adhesive strength. In contrast, the (semi-)additive method requires roughening of the insulating layer before plating to ensure adhesion between the insulating layer and the conductor layer, complicating the circuit formation process (see Patent Documents 1 and 2). Furthermore, when forming fine wiring, the increased surface unevenness can easily reduce the accuracy of circuit formation. Furthermore, a method for manufacturing a printed wiring board has been disclosed (Patent Document 3), in which a highly heat-resistant insulating resin layer is formed on the outermost layer of a core substrate and a conductor circuit is formed on the insulating resin layer. However, this manufacturing method requires roughening of the insulating layer and does not solve the conventional problems.

[0003] Japanese Patent Application Laid-Open No. 2003-69218 Japanese Patent Application Laid-Open No. 2003-249751 Japanese Patent Application Laid-Open No. 2004-6773

[0004] As described above, methods for forming fine wiring patterns have been investigated, but have not been satisfactory. In particular, there is a need for a multilayer body that allows the formation of a fine wiring pattern and has excellent adhesion between the fine wiring pattern and an insulating layer. The present invention aims to solve this problem by providing a multilayer body that allows the formation of a fine wiring pattern and has excellent adhesion between the fine wiring pattern and an insulating layer, and a method for manufacturing a printed wiring board.

[0005] In light of the above-mentioned problems, the present inventors conducted research and found that the above-mentioned problems can be solved by using a predetermined resin component in the insulating layer. Specifically, the above-mentioned problems have been solved by the following means. <1> A multilayer body comprising a metal foil having a surface roughness Rz of 2 μm or less on at least one side in accordance with JIS B0601 1994, and a resin composition-containing layer provided on the surface of the metal foil having a surface roughness Rz of 2 μm or less, wherein the resin composition includes a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher (however, the thermosetting compound may be a thermosetting compound having an unshared electron pair). <2> The multilayer body according to <1>, wherein the compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher and / or the thermosetting compound having an unshared electron pair contains a heteroatom. <3> The multilayer body according to <1> or <2>, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher, and / or the thermosetting compound having an unshared electron pair, includes at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound. <4> The multilayer body according to any one of <1> to <3>, wherein the resin composition includes a maleimide compound. <5> The multilayer body according to any one of <1> to <4>, wherein the resin composition further includes a filler. <6> The multilayer body according to any one of <1> to <5>, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair has a heteroatom, the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound, and the resin composition comprises a maleimide compound. <7> The multilayer body according to <6>, wherein the resin composition further comprises a filler.<8> The multilayer body according to any one of <1> to <7>, wherein the content of the cyanate ester compound contained in the resin composition is less than 1 part by mass per 100 parts by mass of resin solids. <9> The multilayer body according to any one of <1> to <8>, which is used for producing a printed wiring board. <10> The multilayer body according to any one of <1> to <9>, wherein the resin composition-containing layer is a resin sheet formed from the resin composition. <11> The multilayer body according to any one of <1> to <10>, wherein the resin composition-containing layer is a prepreg formed from a substrate and the resin composition. <12> The multilayer body according to <11>, wherein the substrate is glass cloth. <13> The multilayer body according to any one of <1> to <12>, further comprising an inner layer circuit board, wherein the resin composition-containing layer is provided on and in contact with the inner layer circuit board. <14> A multilayer body comprising: a metal foil having a surface roughness Rz of 2 μm or less on at least one side in accordance with JIS B0601 1994; and an insulating layer which is a cured product of a resin composition-containing layer provided on the surface of the metal foil having a surface roughness Rz of 2 μm or less, wherein the resin composition contains a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher (however, the thermosetting compound may be a thermosetting compound having an unshared electron pair). <15> The multilayer body according to <14>, wherein the compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher and / or the thermosetting compound having an unshared electron pair contains a heteroatom. <16> The multilayer body according to <14> or <15>, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher, and / or the thermosetting compound having an unshared electron pair, comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound. <17> The multilayer body according to any one of <14> to <16>, wherein the resin composition comprises a maleimide compound. <18> The multilayer body according to any one of <14> to <17>, wherein the resin composition further comprises a filler.<19> The multilayer body according to any one of <14> to <18>, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair has a heteroatom, the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound, and the resin composition comprises a maleimide compound. <20> The multilayer body according to <19>, wherein the resin composition further comprises a filler. <21> The multilayer body according to any one of <14> to <20>, wherein the content of the cyanate ester compound in the resin composition is less than 1 part by mass per 100 parts by mass of resin solids. <22> The multilayer body according to any one of <14> to <21>, wherein the resin composition-containing layer is a resin sheet formed from the resin composition. <23> The multilayer body according to any one of <14> to <22>, wherein the resin composition-containing layer is a prepreg formed from a substrate and the resin composition. <24> The multilayer body according to any one of <14> to <23>, further comprising an inner layer circuit board, wherein the insulating layer is provided on and in contact with the inner layer circuit board. <25> The multilayer body according to any one of <14> to <24>, wherein, when the metal foil is removed from the multilayer body and the surface of the insulating layer is subjected to an electroless plating treatment and an electrolytic plating treatment, the peel strength is 0.35 kN / m or more. <26> A method for manufacturing a printed wiring board, comprising: removing the metal foil from the multilayer body according to any one of <14> to <25>; performing electroless plating on the surface of the insulating layer from which the metal foil has been removed to form an electroless plated layer; forming a desired resist pattern on the surface of the electroless plated layer; performing plating on the surface on which the desired resist pattern has been formed to form a second plated layer; removing the resist pattern; and etching a portion of the electroless plated layer to expose the insulating layer and form a desired wiring pattern.<27> The method for manufacturing a printed wiring board according to <26>, wherein the line width and space width of the wiring pattern are each 2 μm or less.

[0006] The present invention makes it possible to provide a multilayer body that allows the formation of a fine wiring pattern and has excellent adhesion between the fine wiring pattern and an insulating layer, and a method for producing a printed wiring board.

[0007] 1A and 1B are schematic diagrams illustrating an example of a multilayer body according to an embodiment of the present invention, and 2A and 2B are schematic diagrams illustrating an example of a method for manufacturing a printed wiring board using the multilayer body according to an embodiment of the present invention.

[0008] Hereinafter, a detailed description of an embodiment of the present invention (hereinafter simply referred to as "the present embodiment") will be given. Note that the following present embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, the term "to" is used to mean that the numerical values ​​before and after it are included as the upper and lower limits. Furthermore, any combination of the upper and lower limit values ​​of numerical values ​​in this specification is cited as an example of this embodiment. In this specification, various physical property values ​​and characteristic values ​​are those at 23°C unless otherwise specified. In this specification, when a group (atomic group) is described without specifying whether it is substituted or unsubstituted, it encompasses both a group (atomic group) that has no substituent and a group (atomic group) that has a substituent. For example, the term "alkyl group" encompasses not only an alkyl group that has no substituent (unsubstituted alkyl group) but also an alkyl group that has a substituent (substituted alkyl group). In this specification, when a term without specifying whether it is substituted or unsubstituted, it is preferred that it be unsubstituted. Examples of the substituent herein are preferably a halogen atom, a cyano group, a nitro group, a hydroxy group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a heterocyclicoxy group, an alkenyl group, an alkylsulfanyl group, an arylsulfanyl group, an acyl group, or an amino group, more preferably a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkenyl group, or an acyl group, even more preferably an alkyl group, an aryl group, an aryloxy group, or an alkenyl group, and still more preferably an alkyl group. The formula weight of these substituents is preferably 15 or more, and preferably 200 or less. The formula weight is, for example, ３ ) is 15. These substituents may further have a substituent, but it is preferable that they have no substituent.

[0009] In this specification, "(meth)allyl" refers to either or both of allyl and methallyl, "(meth)acrylate" refers to either or both of acrylate and methacrylate, "(meth)acrylic" refers to either or both of acrylic and methacrylic, and "(meth)acryloyl" refers to either or both of acryloyl and methacryloyl.

[0010] In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the process achieves its intended effect. If the measurement methods described in the standards shown in this specification vary from year to year, they will be based on the standards in effect as of January 1, 2023, unless otherwise specified. If the measurement methods described in the standards shown in this specification are discontinued as of January 1, 2023, they will be based on the standards in effect at the time of discontinuation. In this specification, surface roughness Rz refers to the ten-point average roughness measured in accordance with JIS B0601 1994, unless otherwise specified. The scales in Figures 1 and 2 may not be consistent with reality.

[0011] The melting point in this specification was measured using a differential scanning calorimeter ("DSC7020" manufactured by Hitachi High-Tech Science Corporation). Under a nitrogen atmosphere, the sample was subjected to the following thermal history conditions. The thermal history conditions were a temperature rise rate of 10°C / min and a temperature range of -50°C to 400°C. The melting point is the value read from the peak top value of the observed endothermic peak.

[0012] In this specification, the term "resin solids" refers to components excluding fillers and solvents, and is intended to include thermosetting compounds, compounds having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher, and other resin additive components. In this specification, the terms "relative permittivity" and "dielectric constant" are used interchangeably.

[0013] The first multilayer body of the present embodiment is a multilayer body comprising: a metal foil having a surface roughness Rz of 2 μm or less on at least one side in accordance with JIS B0601 1994; and a resin composition-containing layer provided on the surface of the metal foil having a surface roughness Rz of 2 μm or less, wherein the resin composition contains a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher (however, the thermosetting compound may be a thermosetting compound having an unshared electron pair).

[0014] The second multilayer body of this embodiment is a multilayer body having a metal foil on at least one side having a surface roughness Rz of 2 μm or less in accordance with JIS B0601 1994, and an insulating layer which is a cured product of a resin composition-containing layer provided on the surface of the metal foil having a surface roughness Rz of 2 μm or less, wherein the resin composition includes a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher (however, the thermosetting compound may be a thermosetting compound having an unshared electron pair). The second multilayer body is a multilayer body in which the resin component of the resin composition-containing layer, which will be described in detail later, in the first multilayer body is cured and becomes an insulating layer.

[0015] The use of the multilayer body of this embodiment makes it possible to form a fine wiring pattern, and it is possible to provide a multilayer body and a printed wiring board having excellent adhesion between the fine wiring pattern and an insulating layer. The reason for this is presumably due to the fact that the surface roughness Rz of the metal foil in contact with the insulating layer, which is a resin composition-containing layer having a predetermined composition or a cured product of the resin composition-containing layer, is 2 μm or less. It is presumed that the use of such a metal foil reduces the surface roughness derived from the metal foil that is transferred to the insulating layer, which is a resin composition-containing layer or a cured product of the resin composition-containing layer, or that no roughness is transferred at all. In the production of printed wiring boards, if the surface roughness of the insulating layer, which is a resin composition-containing layer or a cured product of the resin composition-containing layer, is low, adhesion with a plating layer applied in a subsequent process tends to be poor. However, in this embodiment, it is presumed that the use of an insulating layer formed from a predetermined resin composition ensures sufficiently good adhesion with the plating layer. In this way, the use of an insulating layer formed from a predetermined resin composition improves the adhesion between the insulating layer and the plating layer, thereby improving the adhesion between the formed wiring pattern and the insulating layer compared to conventional methods, and as a result, it is presumed that a finer wiring pattern than conventional methods can be formed. In particular, in this embodiment, by providing a plating layer on the surface of an insulating layer adjusted to a specific surface roughness and formed from a predetermined resin composition by electroless plating, it is presumed that the adhesion between the insulating layer and the plating layer, and therefore between the insulating layer and the wiring pattern, can be further improved, and that an even finer wiring pattern can be formed. In addition, since the wiring pattern can be formed on an insulating layer with a small surface roughness derived from the metal foil, there is an advantage that a semiconductor device with small conductor loss and small energy loss can be obtained.

[0016] <Metal Foil> The multilayer body of this embodiment has a metal foil having a surface roughness Rz of 2 μm or less on at least one side according to JIS B0601 1994. The Rz of the metal foil is preferably 2.0 μm or less, more preferably 1.8 μm or less, even more preferably 1.5 μm or less, and may be 1.0 μm or less. Furthermore, while the Rz of the metal foil is practically greater than 0 μm, it is preferably 0.2 μm or more, more preferably 0.5 μm or more, and may even be greater than 0.5 μm, 0.6 μm, or 0.7 μm or more. By setting the Rz of the metal foil to the above upper limit or less, the time required for the process of removing the metal foil by etching tends to be further shortened. Furthermore, the time required for the flash etching process (etching a portion of the electroless plating layer to expose the insulating layer) can be further shortened, which tends to facilitate the formation of a wiring pattern with smaller lines and / or spaces. Furthermore, by making the Rz of the metal foil equal to or greater than the lower limit, the adhesion between the insulating layer and the plating layer tends to be further improved.

[0017] The thickness of the metal foil is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.0 μm or more, still more preferably 1.2 μm or more, and may be 1.5 μm or more. The thickness of the metal foil is preferably 5.0 μm or less, more preferably 4.0 μm or less, even more preferably 3.0 μm or less, and may be 2.5 μm or less, or 2.0 μm or less. By making the thickness of the metal foil equal to or greater than the lower limit, the adhesion between the insulating layer and the plating layer tends to be further improved. By making the thickness equal to or less than the upper limit, the time required for the process of removing the metal foil by etching tends to be further shortened.

[0018] Examples of the metal constituting the metal foil include at least one metal selected from copper, aluminum, nickel, titanium, iron, gold, silver, platinum, tin, zinc, tantalum, molybdenum, niobium, and other alloys, and copper is more preferred.

[0019] As described above, the metal foil is preferably copper foil, but in this embodiment, it may be either rolled copper foil or electrolytic copper foil. Furthermore, the metal foil may be subjected to various surface treatments on its surface, which has a surface roughness Rz of 2 μm or less. Examples of such treatments include roughening treatment, heat-resistant treatment, rust-proofing treatment, and silane coupling agent treatment. The metal foil may be subjected to any one of these treatments, or a combination of two or more of them. When two or more of the above treatments are performed, the order of the treatments is preferably roughening treatment, heat-resistant treatment, rust-proofing treatment, and silane coupling agent treatment. These treatments can be any known surface treatment for metal foil.

[0020] The method for providing the metal foil on the surface of the resin composition-containing layer is not particularly limited, and for example, the resin composition of the present embodiment can be applied to the metal foil by dissolving the resin composition in a solvent (varnish) and then drying the applied varnish. Examples of application methods include a gravure coater, a bar coater, a die coater, a doctor blade, and a baker applicator.

[0021] In this embodiment, it is preferable to use a metal foil with a carrier support, which is a metal foil and a carrier support laminated together, to provide the metal foil on the surface of the resin composition-containing layer.Specifically, for example, a thin copper foil with a carrier copper foil, which has a thickness of 1.5 μm and a surface roughness Rz of 2 μm or less as the metal foil, and a thin copper foil with a carrier copper foil, which has a thickness of 18 μm as the carrier support, is arranged on the surface of a resin sheet or prepreg, which will be described later in detail, so that the surface with a surface roughness Rz of 2 μm or less is in contact with the surface, and then laminate-molded, and then the carrier copper foil is removed, so that the metal foil can be provided on the surface of the resin composition-containing layer.

[0022] Examples of the carrier support include metal foil and resin film, with metal foil being preferred and copper foil being more preferred. When the carrier support is copper foil, it is often referred to as carrier copper foil. For resin films, the description in paragraph 0031 of WO 2017 / 086418 can be referred to, the contents of which are incorporated herein by reference. The thickness of the carrier support is, for example, 5 μm or more, preferably 8 μm or more, and 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 30 μm or less. The metal foil with a carrier support may have other layers (such as an adhesive layer, a release layer, a roughening treatment layer, a heat-resistant treatment layer, a rust-proofing treatment layer, or a silane coupling agent treatment layer) provided between the carrier support and the metal foil.

[0023] <Resin Composition-Containing Layer> The multilayer body (first multilayer body) of this embodiment has a resin composition-containing layer provided on a surface of a metal foil having a surface roughness Rz of 2 μm or less. The resin composition contains a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher (however, the thermosetting compound may be a thermosetting compound having an unshared electron pair). The compound having a melting point of 10° C. or higher includes a compound that is solid at least at 23° C.

[0024] In this embodiment, the compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher and / or the thermosetting compound having an unshared electron pair preferably contains a heteroatom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom, and an oxygen atom and / or a nitrogen atom are more preferred.

[0025] A compound having an unshared electron pair, an aromatic ring, and a melting point of 10°C or higher has an aromatic ring. The aromatic ring tends to facilitate the development of adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern). The aromatic ring preferably contains a benzene ring and / or a heterocycle, and may be a condensed ring, but is preferably a monocycle. The heterocycle is preferably a nitrogen-containing heterocycle, more preferably a triazine ring.

[0026] Furthermore, a compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher has a melting point of 10°C or higher. A melting point of 10°C or higher tends to further improve heat resistance. The melting point is preferably 30°C or higher, more preferably 50°C or higher, even more preferably 70°C or higher, even more preferably 90°C or higher, and even more preferably 100°C or higher, and is preferably 380°C or lower, more preferably 360°C or lower, even more preferably 340°C or lower, even more preferably 320°C or lower, and even more preferably 300°C or lower. By setting the melting point to the above upper limit or lower, the flexibility of the cured product tends to further improve. When the resin composition contains two or more compounds having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher, it is preferable that the weighted average of the melting points of the respective compounds satisfies the above range.

[0027] The molecular weight of the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher is preferably 100 or higher, more preferably 150 or higher, even more preferably 200 or higher, even more preferably 250 or higher, and even more preferably 300 or higher, and preferably 300,000 or lower, more preferably 250,000 or lower, even more preferably 200,000 or lower, even more preferably 150,000 or lower, and even more preferably 100,000 or lower. By setting the molecular weight to the above lower limit or higher, the viscosity of the resin composition tends to be improved, and the varnish coatability on metal foil and the effect of suppressing thickness variation when laminating a multilayer body to a substrate tend to be further improved. Furthermore, by setting the molecular weight to the above upper limit or lower, the melt viscosity of the resin composition tends to be further reduced, and the laminate moldability onto circuit boards tends to be excellent. When the resin composition contains two or more compounds having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher, it is preferable that the weighted average molecular weight of each compound satisfies the above range.

[0028] In this embodiment, the compound having an unshared electron pair, an aromatic ring, and a melting point of 10° C. or higher is preferably a compound having one or more structures selected from the following structures: In the above compound, each R is independently a hydrogen atom or a substituent. In the above compound, R is preferably a substituent.

[0029] On the other hand, the molecular weight of the thermosetting compound having an unshared electron pair is preferably 100 or more, more preferably 150 or more, even more preferably 200 or more, even more preferably 250 or more, and even more preferably 300 or more, and is preferably 300,000 or less, more preferably 250,000 or less, even more preferably 200,000 or less, even more preferably 150,000 or less, and even more preferably 100,000 or less. By setting the molecular weight to the above lower limit or more, the adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern) tends to be further improved. Furthermore, by setting the molecular weight to the above upper limit or less, the melt viscosity of the resin composition tends to be further reduced, and the laminate moldability onto the circuit board tends to be excellent. When the resin composition contains two or more thermosetting compounds having an unshared electron pair, it is preferable that the weighted average molecular weight of each compound satisfies the above range.

[0030] Specific examples of the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair include at least one selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound.

[0031] The total content of the compound having an unshared electron pair and an aromatic ring, and having a melting point of 10°C or higher, and the thermosetting compound having an unshared electron pair (preferably the total content of compounds selected from the group consisting of polyphenylene ether compounds having a terminal carbon-carbon unsaturated double bond, phosphate ester compounds, and cyanate ester compounds) in the resin composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the resin solids in the resin composition. Depending on the application, it may be 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, or even 50 parts by mass or more. By setting the content at or above the lower limit, adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern) and fine wiring formability tend to be further improved. The upper limit of the total content is preferably 99 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition, and may be 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less, depending on the application, etc. By setting the content to the upper limit or less, laminate moldability onto a circuit board tends to be further improved.

[0032] <<Polyphenylene Ether Compound Having a Terminal Carbon-Carbon Unsaturated Double Bond>> The resin composition preferably contains a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond. By containing a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond in the resin composition, the adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern) and the ability to form fine wiring are further improved. The polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond is preferably a polyphenylene ether compound having two or more terminal carbon-carbon unsaturated double bonds, more preferably a polyphenylene ether compound having two or more terminal groups selected from the group consisting of (meth)acryloyl groups, (meth)allyl groups, and vinylbenzyl groups, and even more preferably a polyphenylene ether compound having two or more terminal groups selected from the group consisting of (meth)acryloyl groups and vinylbenzyl groups. The use of these polyphenylene ether compounds tends to improve the adhesion between the insulating layer and the metal layer (plated layer and / or wiring pattern) and the ability to form fine wiring, as well as to more effectively improve the low dielectric properties, low water absorption, etc. of printed wiring boards, etc. These will be described in detail below.

[0033] The polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond is exemplified by a compound having a phenylene ether skeleton represented by the following formula (X1):

[0034] (In formula (X1), R ２４ , R ２５ , R ２６ , and R ２７ may be the same or different and represent an alkyl group having 6 or less carbon atoms, an aryl group, a halogen atom, or a hydrogen atom.

[0035] The polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond is represented by the formula (X2): (In formula (X2), R ２８ , R ２９ , R ３０ , R ３４ , and R ３５may be the same or different and represent an alkyl group having 6 or less carbon atoms or a phenyl group. ３１ , R ３２ , and R ３３ may be the same or different and are a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group.) and / or a structural unit represented by formula (X3): (In formula (X3), R ３６ , R ３７ , R ３８ , R ３９ , R ４０ , R ４１ , R ４２ , and R ４３ may be the same or different and are a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. -A- is a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms.

[0036] The polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond is preferably a modified polyphenylene ether compound in which some or all of the terminals are functionalized with ethylenically unsaturated groups (hereinafter sometimes referred to as "modified polyphenylene ether compound (g)"). It is more preferably a modified polyphenylene ether compound having two or more terminal groups selected from the group consisting of (meth)acryloyl groups, (meth)allyl groups, and vinylbenzyl groups, and even more preferably a modified polyphenylene ether compound having two or more terminal groups selected from the group consisting of (meth)acryloyl groups and vinylbenzyl groups. The use of such modified polyphenylene ether compound (g) not only improves the adhesion between the insulating layer and the metal layer (plated layer and / or wiring pattern) and the ability to form fine wiring, but also reduces the dielectric loss tangent (Df) of the cured product of the resin composition and enhances its low water absorption. The modified polyphenylene ether compound (g) may be used alone or in combination of two or more types.

[0037] The modified polyphenylene ether compound (g) may be a polyphenylene ether compound represented by formula (OP). (In formula (OP), X represents an aromatic group, and —(Y—O) ｎ１ - represents a polyphenylene ether structure, n1 represents an integer of 1 to 100, and n2 represents an integer of 1 to 4. Rx is a group represented by formula (Rx-1) or formula (Rx-2). (In formula (Rx-1) and formula (Rx-2), R １ , R ２ , and R ３ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. * represents a bonding site with an oxygen atom. Each Mc independently represents a hydrocarbon group having 1 to 12 carbon atoms. z represents an integer of 0 to 4. r represents an integer of 1 to 6.

[0038] n １ and / or n ２ When n is an integer of 2 or more, １ n structural units (Y-O) and / or n ２ The n constitutional units may be the same or different. ２ is preferably 2 or more, more preferably 2.

[0039] In formula (Rx-1) and formula (Rx-2), R １ , R ２ , and R ３ R each independently represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. １ is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. ２ and R ３ are each independently preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. １ , R ２ , and R ３ The number of carbon atoms in each of the alkyl group, alkenyl group, and alkynyl group is preferably 5 or less, and more preferably 3 or less.

[0040] In formula (Rx-1), r represents an integer of 1 to 6, preferably an integer of 1 to 5, more preferably an integer of 1 to 4, even more preferably an integer of 1 to 3, still more preferably 1 or 2, and even more preferably 1.

[0041] In formula (Rx-1), each Mc independently represents a hydrocarbon group having 1 to 12 carbon atoms, preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a linear or branched alkyl group having 1 to 10 carbon atoms, still more preferably a methyl group, ethyl group, isopropyl group, isobutyl group, t-butyl group, pentyl group, octyl group, or nonyl group, and even more preferably a methyl group, ethyl group, isopropyl group, isobutyl group, or t-butyl group. In formula (Rx-1), z represents an integer of 0 to 4, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, still more preferably 0 or 1, and still more preferably 0.

[0042] A specific example of the group represented by formula (Rx-1) is a vinylbenzyl group, and a specific example of the group represented by formula (Rx-2) is a (meth)acryloyl group.

[0043] The modified polyphenylene ether compound (g) is preferably a compound represented by formula (OP-1). (In formula (OP-1), X represents an aromatic group, and —(Y—O)n ２ - represents a polyphenylene ether structure, and R １ , R ２ , and R ３ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group; n １ represents an integer of 1 to 6, and n ２ represents an integer from 1 to 100, and n ３ represents an integer of 1 to 4. ２ and / or n ３ When n is an integer of 2 or more, ２ n structural units (Y-O) and / or n ３ The n constitutional units may be the same or different. ３ is preferably 2 or more, more preferably 2.

[0044] The modified polyphenylene ether compound (g) in this embodiment is preferably a compound represented by formula (OP-2). Here, -(O-X-O)- represents the formula (OP-3): (In formula (OP-3), R ４ , R ５ , R ６ , R １０ , and R １１ may be the same or different and are alkyl groups or phenyl groups having 6 or less carbon atoms. ７ , R ８ , and R ９ may be the same or different and are a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group.) and / or a group represented by formula (OP-4): (In formula (OP-4), R １２ , R １３ , R １４ , R １５ , R １６ , R １７ , R １８ , and R １９ may be the same or different and are a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. -A- is a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms.

[0045] In addition, -(Y-O)- represents a group represented by formula (OP-5): (In formula (OP-5), R ２０ , R ２１ may be the same or different and are alkyl groups or phenyl groups having 6 or less carbon atoms. ２２ , R ２３ may be the same or different and are a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. ２０ and R ２１are each independently a group having one or more methyl groups and / or cyclohexyl groups, the rigidity of the resulting resin molecules is increased, and since highly rigid molecules have lower mobility than less rigid molecules, the relaxation time during dielectric relaxation is longer, resulting in excellent low dielectric properties (Dk and / or Df), which is preferable. An example of formula (OP-5) is the following structure. For the polyphenylene compound having the above structure, the description in JP 2019-194312 A can be referred to, the contents of which are incorporated herein by reference.

[0046] In formula (OP-2), a and b each independently represent an integer of 0 to 100, and at least one of a and b is an integer of 1 to 100. a and b each independently represent an integer of 0 to 50, more preferably an integer of 1 to 30, and preferably an integer of 1 to 10. When a and / or b is an integer of 2 or greater, two or more -(Y-O)- groups may each independently represent an arrangement of one type of structure, or two or more types of structures may be arranged in blocks or randomly. Furthermore, when a compound represented by formula (OP-2) is contained, the average value of a preferably satisfies 1<a<10, and the average value of b preferably satisfies 1<b<10.

[0047] Examples of -A- in formula (OP-4) include divalent organic groups such as a methylene group, an ethylidene group, a 1-methylethylidene group, a 1,1-propylidene group, a 1,4-phenylenebis(1-methylethylidene) group, a 1,3-phenylenebis(1-methylethylidene) group, a cyclohexylidene group, a phenylmethylene group, a naphthylmethylene group, and a 1-phenylethylidene group, but are not limited to these.

[0048] Among the compounds represented by the above formula (OP-2), R ４ , R ５ , R ６ , R １０ , R １１ , R ２０ , and R ２１ is an alkyl group having 3 or less carbon atoms, and R ７ , R ８ , R９ , R １２ , R １３ , R １４ , R １５ , R １６ , R １７ , R １８ , R １９ , R ２２ , and R ２３ is a hydrogen atom or an alkyl group having 3 or less carbon atoms, and it is particularly preferred that -(O-X-O)- represented by formula (OP-3) or formula (OP-4) is formula (OP-9), formula (OP-10), and / or formula (OP-11), and that -(Y-O)- represented by formula (OP-5) is formula (OP-12) or formula (OP-13). When a and / or b are integers of 2 or more, the two or more -(Y-O)- may each independently be a structure in which two or more of formula (OP-12) and / or formula (OP-13) are arranged, or a structure in which formula (OP-12) and formula (OP-13) are arranged in blocks or randomly.

[0049] (In formula (OP-10), R ４４ , R ４５ , R ４６ , and R ４７ may be the same or different and are a hydrogen atom or a methyl group. -B- is a linear, branched or cyclic divalent hydrocarbon group having 20 or less carbon atoms. Specific examples of -B- include the same as the specific examples of -A- in formula (OP-4). (In formula (OP-11), -B- represents a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms.) Specific examples of -B- include the same as the specific examples of -A- in formula (OP-4).

[0050] The polyphenylene ether compound used in the present embodiment is more preferably a compound represented by formula (OP-14) and / or a compound represented by formula (OP-15), and even more preferably a compound represented by formula (OP-15). (In formula (OP-14), a and b each independently represent an integer of 0 to 100, and at least one of a and b is an integer of 1 to 100.) a and b in formula (OP-14) each independently have the same meanings as a and b in formula (OP-2), and the preferred ranges are also the same. (In formula (OP-15), a and b each independently represent an integer of 0 to 100, and at least one of a and b is an integer of 1 to 100.) a and b in formula (OP-15) each independently have the same meanings as a and b in formula (OP-2), and the preferred ranges are also the same.

[0051] In addition, the polyphenylene ether compound used in this embodiment may also be a compound represented by formula (OP-16). (In formula (OP-16), a and b each independently represent an integer of 0 to 100, and at least one of a and b is an integer of 1 to 100.) a and b in formula (OP-16) each independently have the same meanings as a and b in formula (OP-2), and the preferred ranges are also the same.

[0052] The polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond may be produced by a known method, or a commercially available product may be used. Examples of commercially available products include "SA9000" manufactured by SABIC Innovative Plastics, which is a modified polyphenylene ether compound having a terminal methacryloyl group. Examples of modified polyphenylene ether compounds having a terminal vinylbenzyl group include "OPE-2St1200" and "OPE-2st2200" manufactured by Mitsubishi Gas Chemical Company. Examples of modified polyphenylene ether compounds having a terminal hydroxyl group, such as "SA90" manufactured by SABIC Innovative Plastics, which have been modified to a vinylbenzyl group using vinylbenzyl chloride or the like, may also be used as modified polyphenylene ether compounds having a terminal hydroxyl group.

[0053] In addition, for details of polyphenylene ether compounds having terminal carbon-carbon unsaturated double bonds, see JP 2006-028111 A, JP 2018-131519 A, WO 2019-138992, and WO 2022-054303. The contents of these publications are incorporated herein by reference.

[0054] The polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond (preferably a modified polyphenylene ether compound (g)) preferably has a polystyrene-equivalent number average molecular weight (details follow the method described in the Examples below) measured by GPC (gel permeation chromatography) of 500 or more and 3,000 or less. A number average molecular weight of 500 or more tends to further suppress stickiness when the resin composition is formed into a coating film. A number average molecular weight of 3,000 or less tends to further improve solubility in solvents. Furthermore, the polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond (preferably a modified polyphenylene ether compound (g)) preferably has a polystyrene-equivalent weight average molecular weight (details follow the method described in the Examples below) measured by GPC of 800 or more and 10,000 or less, more preferably 800 or more and 5,000 or less. By setting the content at or above the lower limit, the dielectric constant (Dk) and / or dielectric dissipation factor (Df) of the cured product of the resin composition tends to be lower, while by setting the content at or below the upper limit, the solubility, low viscosity, and moldability of the resin composition in solvents when preparing varnishes, etc., as described below, tend to be further improved. Furthermore, in the case of the modified polyphenylene ether compound (g), the terminal carbon-carbon unsaturated double bond equivalent is preferably 400 to 5,000 g per carbon-carbon unsaturated double bond, and more preferably 400 to 2,500 g. By setting the content at or above the lower limit, the dielectric constant (Dk) and / or dielectric dissipation factor (Df) of the cured product of the resin composition tends to be lower. By setting the content at or below the upper limit, the solubility, low viscosity, and moldability of the resin composition in solvents tend to be further improved.

[0055] When the resin composition contains a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, the lower limit of its content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 13 parts by mass or more, per 100 parts by mass of the resin solids in the resin composition. By setting the content at or above the lower limit, the adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern) and the ability to form fine wiring are further improved, and the low dielectric properties (Dk and / or Df) and moisture absorption heat resistance of the resulting cured product (insulating layer) tend to be more excellent. Furthermore, the upper limit of the content of the polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less, per 100 parts by mass of the resin solids in the resin composition. By setting the content to be equal to or less than the upper limit, the adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern) and the heat resistance and chemical resistance of the resulting cured product (insulating layer) tend to be better. The resin composition in this embodiment may contain only one type of polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0056] <<Phosphate Ester Compound>> The resin composition may contain a phosphate ester compound. By containing the phosphate ester compound, an insulating layer excellent in adhesion to a metal layer (plated layer and / or wiring pattern), fine wiring formability, and flame retardancy can be obtained. As the phosphate ester compound, a condensed phosphate ester compound is preferred, and a condensed phosphate ester compound represented by the following formula (P) is more preferred. Formula (P)

[0057] The condensed phosphate ester compound represented by formula (P) may be a mixture of compounds having different k values ​​in formula (P), and in the case of a mixture of condensed phosphate esters having different k values, k is the average value of the mixture. k is usually an integer from 0 to 5, and in the case of a mixture of compounds having different k values, the average k value is preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.8 or more, particularly preferably 0.95 or more, and is preferably 2 or less, more preferably 1.5 or less, even more preferably 1.2 or less, particularly preferably 1.15 or less.

[0058] Also, X １ represents a divalent arylene group, and examples thereof include divalent groups derived from dihydroxy compounds such as resorcinol, hydroquinone, bisphenol A, 2,2'-dihydroxybiphenyl, 2,3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene. Of these, divalent groups derived from resorcinol, bisphenol A, and 3,3'-dihydroxybiphenyl are particularly preferred.

[0059] In formula (P), p, q, r and s each independently represent 0 or 1, with 1 being preferred.

[0060] R in formula (P) １１ , R １２ , R １３ and R １４and each represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms which may be substituted with an alkyl group. Examples of such an aryl group include a phenyl group, a cresyl group, a xylyl group, an isopropylphenyl group, a butylphenyl group, a tert-butylphenyl group, a di-tert-butylphenyl group, and a p-cumylphenyl group, with a phenyl group, a cresyl group, and a xylyl group being more preferred.

[0061] Specific examples of the condensed phosphate ester compound represented by formula (P) include aromatic phosphate esters such as triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), cresyl diphenyl phosphate (CDP), 2-ethylhexyl diphenyl phosphate (EHDP), tert-butylphenyl diphenyl phosphate, bis-(tert-butylphenyl)phenyl phosphate, tris-(tert-butylphenyl)phosphate, isopropylphenyl diphenyl phosphate, bis-(isopropylphenyl)diphenyl phosphate, and tris-(isopropylphenyl)phosphate; and condensed phosphate esters such as resorcinol bis-diphenyl phosphate (RDP), resorcinol bis-dixylenyl phosphate (RDX), bisphenol A bis-diphenyl phosphate (BDP), and biphenyl bis-diphenyl phosphate. Among these, resorcinol bis-dixylenyl phosphate (RDX) is preferred in terms of low dielectric properties.

[0062] The acid value of the condensed phosphate ester compound represented by formula (P) is preferably 0.2 mgKOH / g or less, more preferably 0.15 mgKOH / g or less, even more preferably 0.1 mgKOH or less, and particularly preferably 0.05 mgKOH / g or less. The lower limit of the acid value can be set to substantially 0. Furthermore, the content of the half ester of the condensed phosphate ester compound represented by formula (P) is preferably 1 mass% or less, more preferably 0.5 mass% or less. By setting the acid value to 0.2 mgKOH / g or less and the half ester content to 1 mass% or less, the thermal stability of the resulting cured product (insulating layer) tends to be further improved.

[0063] When the resin composition contains a phosphate ester compound, the lower limit of its content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and may even be 15 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. Furthermore, the lower limit of the phosphate ester compound content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. By setting the content of the phosphate ester compound within the above range, the adhesion between the insulating layer and the metal layer (plating layer and / or wiring pattern) and the ability to form fine wiring are further improved. The resin composition may contain only one type of phosphate ester compound, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0064] <<Cyanate Ester Compound>> The resin composition preferably contains a cyanate ester compound. By including a cyanate ester compound in the resin composition, the adhesion between the insulating layer and the metal layer (plated layer and / or wiring pattern) and the ability to form fine wiring are further improved. The cyanate ester compound is not particularly limited as long as it contains one or more cyanate groups (cyanato groups) per molecule (preferably 2 to 12, more preferably 2 to 6, even more preferably 2 to 4, even more preferably 2 or 3, and even more preferably 2), and a wide range of compounds commonly used in the field of printed wiring boards can be used. Furthermore, the cyanate ester compound is preferably a compound in which the cyanate group is directly bonded to an aromatic skeleton (aromatic ring). Examples of the cyanate ester compound include at least one selected from the group consisting of phenol novolac-type cyanate ester compounds, naphthol aralkyl-type cyanate ester compounds (naphthol aralkyl-type cyanates), naphthylene ether-type cyanate ester compounds, biphenyl aralkyl-type cyanate ester compounds, xylene resin-type cyanate ester compounds, trisphenolmethane-type cyanate ester compounds, adamantane skeleton-type cyanate ester compounds, bisphenol M-type cyanate ester compounds, bisphenol A-type cyanate ester compounds, and diallyl bisphenol A-type cyanate ester compounds. Among these, from the viewpoint of further improving the low water absorption of the resulting cured product (insulating layer), at least one selected from the group consisting of phenol novolac-type cyanate ester compounds, naphthol aralkyl-type cyanate ester compounds, naphthylene ether-type cyanate ester compounds, xylene resin-type cyanate ester compounds, bisphenol M-type cyanate ester compounds, bisphenol A-type cyanate ester compounds, and diallyl bisphenol A-type cyanate ester compounds is preferred, and naphthol aralkyl-type cyanate ester compounds are more preferred. These cyanate ester compounds may be prepared by known methods, or commercially available products may be used.In addition, cyanate ester compounds having a naphthol aralkyl skeleton, naphthylene ether skeleton, xylene skeleton, trisphenolmethane skeleton, or adamantane skeleton have a relatively large functional group equivalent weight and fewer unreacted cyanate ester groups, so cured resin compositions using these tend to have even better low water absorption. Furthermore, due mainly to the presence of an aromatic skeleton or adamantane skeleton, adhesion to metal layers (plating layers and / or wiring patterns) and fine wiring formability tend to be even more improved. In particular, in this embodiment, naphthol aralkyl cyanate ester compounds represented by formula (7) are preferred. (In formula (7), R ６ Each independently represents a hydrogen atom or a methyl group, and among these, a hydrogen atom is preferred. ２ represents an integer of 1 or more. ２ The upper limit is usually 10, preferably 6. In addition to the above, in this embodiment, the cyanate ester compounds described in WO 2021 / 172317 can be used, the contents of which are incorporated herein by reference.

[0065] The relative dielectric constant at a frequency of 10 GHz of the cured product of the cyanate ester compound used in this embodiment, as measured according to a cavity resonance perturbation method, is preferably 3.0 or less, more preferably 2.9 or less, and even more preferably less than 2.9, with a practical lower limit of 2.4 or more.

[0066] When the resin composition contains a cyanate ester compound, the lower limit of its content is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. A cyanate ester compound content of 0.1 parts by mass or more tends to improve adhesion to the metal layer (plating layer and / or wiring pattern), fine wiring formability, and the resulting cured product (insulating layer) tends to have excellent heat resistance, flame resistance, chemical resistance, low dielectric properties (dielectric constant and / or dielectric dissipation factor), and insulating properties. The upper limit of the cyanate ester compound content is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. It may also be 8 parts by mass or less, or 6 parts by mass or less, depending on the application. The resin composition in this embodiment may contain only one type of cyanate ester compound, or two or more types of cyanate ester compounds. When two or more types are contained, the total amount is preferably within the above range. The resin composition is also preferably configured to be substantially free of cyanate ester compounds. "Substantially free" means that the content of the cyanate ester compound is less than 1 part by mass per 100 parts by mass of the resin solid content, and may be less than 0.5 parts by mass, less than 0.3 parts by mass, or less than 0.1 parts by mass.

[0067] <Thermosetting Compound> The resin composition of this embodiment also contains a thermosetting compound. The thermosetting compound may be a thermosetting compound having an unshared electron pair, such as the polyphenylene ether compound or cyanate ester compound having a terminal carbon-carbon double bond described above, or may be a thermosetting compound without an unshared electron pair. In this embodiment, it is preferable that at least one of the thermosetting compounds is a thermosetting compound having an unshared electron pair. By adopting such a configuration, a cured product (insulating layer) having superior adhesion to the plating layer can be obtained, and the formed wiring pattern can be made finer. In addition to the above, the thermosetting compound preferably includes at least one selected from the group consisting of maleimide compounds, polymers having a structural unit represented by formula (V), (meth)allyl compounds, (meth)acrylate compounds, compounds having an indane skeleton having a terminal carbon-carbon unsaturated double bond, epoxy compounds, phenol compounds, oxetane resins, benzoxazine compounds, arylcyclobutene compounds, perfluorovinyl ether resins, polyamide compounds, polyimide compounds, and compounds having a vinylene group, and more preferably includes a maleimide compound. (In formula (V), Ar represents an aromatic hydrocarbon linking group. * represents a bonding position.)

[0068] When the resin composition contains a thermosetting compound, its content (the total amount of the thermosetting compound having an unshared electron pair and the thermosetting compound not having an unshared electron pair) is preferably 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. Depending on the application, it may be 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, or 50 parts by mass or more. By setting the content of the thermosetting compound to be equal to or greater than the lower limit, heat resistance, plating adhesion, low thermal expansion, etc. tend to be further improved. Furthermore, the upper limit of the content of the thermosetting compound is preferably 99 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. Depending on the application, it may be 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less. By setting the content of the thermosetting compound to the upper limit or less, low dielectric properties and low water absorption tend to be further improved. The resin composition may contain only one type of other thermosetting compound, or may contain two or more types. When two or more types are contained, it is preferable that the total amount is within the above range.

[0069] <<Maleimide Compound>> The resin composition may contain a maleimide compound. The resin composition is not particularly limited as long as it is a compound having one or more (preferably 2 to 12, more preferably 2 to 6, even more preferably 2 to 4, still more preferably 2 or 3, and even more preferably 2) maleimide groups per molecule, and a wide variety of compounds commonly used in the field of printed wiring boards can be used. In this embodiment, the maleimide compound preferably contains one or more selected from the group consisting of a compound represented by formula (M0), a compound represented by formula (M1), a compound represented by formula (M2), a compound represented by formula (M3), a compound represented by formula (M4), a compound represented by formula (M5), a maleimide compound (M6), a maleimide compound (M7), and a maleimide compound (M8). The maleimide compound represented by formula (M0), a compound represented by formula (M1), a compound represented by formula (M2), a compound represented by formula (M3), a compound represented by formula (M4), and a compound represented by formula (M5) may be selected from the group consisting of a compound represented by formula (M0), a compound represented by formula (M1), a compound represented by formula (M2), a compound represented by formula (M3), a compound represented by formula (M4), and a compound represented by formula (M5). It is more preferable that the maleimide compound contains one or more compounds selected from the group consisting of compounds represented by formula (M0), compounds represented by formula (M1), compounds represented by formula (M3), compounds represented by formula (M4), and compounds represented by formula (M5), it is even more preferable that the maleimide compound contains one or more compounds selected from the group consisting of compounds represented by formula (M1), compounds represented by formula (M3), and compounds represented by formula (M5), it is even more preferable that the maleimide compound contains one or more compounds represented by formula (M1) and / or compounds represented by formula (M3). When used in materials for printed wiring boards (e.g., metal foil-clad laminates), etc., it can impart excellent heat resistance.

[0070] (In formula (M0), R ５１ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group; R ５２ each independently represents a hydrogen atom or a methyl group; n １ represents an integer of 1 or more.) R ５１are each independently preferably one selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, and a phenyl group, more preferably a hydrogen atom and / or a methyl group, and even more preferably a hydrogen atom. ５２ is preferably a methyl group. １ is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, even more preferably an integer of 1 to 3, still more preferably 1 or 2, and even more preferably 1. Specifically, preferred examples of formula (M0) include compounds represented by the following formula (M0-1): In the above formula, R ８ each independently represents a hydrogen atom, a methyl group, or an ethyl group, and is preferably a methyl group.

[0071] The compound represented by formula (M0) may be a single compound or a mixture of two or more compounds. Examples of the mixture include compounds such as １ a mixture of compounds with different R ５１ and / or R ５２ a mixture of compounds in which the types of substituents are different, a mixture of compounds in which the bonding positions (meta, para, or ortho positions) of the maleimide group and the oxygen atom relative to the benzene ring are different, and a mixture of compounds in which two or more of the above differences are combined. The same applies to the formulae (M1) to (M7) below.

[0072] (In formula (M1), R Ｍ１ , R Ｍ２ , R Ｍ３ , and R Ｍ４ R each independently represents a hydrogen atom or an organic group. Ｍ５ and R Ｍ６ each independently represents a hydrogen atom or an alkyl group. Ｍ represents a divalent aromatic group. A is a 4- to 6-membered alicyclic group. R Ｍ７ and R Ｍ８ are each independently an alkyl group. mx is 1 or 2, and lx is 0 or 1. R Ｍ９ and R Ｍ１０R each independently represents a hydrogen atom or an alkyl group. Ｍ１１ , R Ｍ１２ , R Ｍ１３ , and R Ｍ１４ R each independently represents a hydrogen atom or an organic group. Ｍ１５ each independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a halogen atom, a hydroxyl group, or a mercapto group. px represents an integer of 0 to 3. nx represents an integer of 1 to 20.

[0073] R in the formula Ｍ１ , R Ｍ２ , R Ｍ３ , and R Ｍ４ R each independently represents a hydrogen atom or an organic group. The organic group here is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably a methyl group, an ethyl group, a propyl group, or a butyl group, with a methyl group being particularly preferred. Ｍ１ and R Ｍ３ are each independently preferably an alkyl group, and R Ｍ２ and R Ｍ４ is preferably a hydrogen atom. Ｍ５ and R Ｍ６ Each of Ar independently represents a hydrogen atom or an alkyl group, and an alkyl group is preferable. The alkyl group here is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and further preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and among these, a methyl group is particularly preferable. Ｍ represents a divalent aromatic group, preferably a phenylene group, a naphthalenediyl group, a phenanthrenediyl group, or an anthracenediyl group, more preferably a phenylene group, and even more preferably an m-phenylene group. Ｍmay have a substituent, and the substituent is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, still more preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and particularly preferably a methyl group. Ｍ A is preferably a 4- to 6-membered alicyclic group, more preferably a 5-membered alicyclic group (preferably a group that forms an indane ring when combined with a benzene ring). Ｍ７ and R Ｍ８ are each independently an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group. mx is 1 or 2, preferably 2. lx is 0 or 1, preferably 1. R Ｍ９ and R Ｍ１０ R each independently represents a hydrogen atom or an alkyl group, with an alkyl group being more preferred. The alkyl group here is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, further preferably a methyl group, an ethyl group, a propyl group, or a butyl group, with a methyl group being particularly preferred. Ｍ１１ , R Ｍ１２ , R Ｍ１３ , and R Ｍ１４ R each independently represents a hydrogen atom or an organic group. The organic group here is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably a methyl group, an ethyl group, a propyl group, or a butyl group, with a methyl group being particularly preferred. Ｍ１２ and R Ｍ１３ are each independently preferably an alkyl group, and R Ｍ１１ and R Ｍ１４ is preferably a hydrogen atom. Ｍ１５each independently represent an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a halogen atom, a hydroxyl group, or a mercapto group, and is preferably an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. px represents an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0. nx represents an integer of 1 to 20. nx may be an integer of 10 or less. The resin composition may contain only one or more compounds represented by formula (M1) having at least different values ​​of nx. When two or more types are contained, the average value of nx (average number of repeating units) n in the compound represented by formula (M1) in the resin composition is preferably 0.92 or more, more preferably 0.95 or more, even more preferably 1.0 or more, and even more preferably 1.1 or more, in order to have a low melting point (low softening point), low melt viscosity, and excellent handleability. Furthermore, n is preferably 10.0 or less, more preferably 8.0 or less, even more preferably 7.0 or less, even more preferably 6.0 or less, and may be 5.0 or less. The same applies to formula (M1-1) described later.

[0074] The compound represented by formula (M1) is preferably a compound represented by the following formula (M1-1): (In formula (M1-1), R Ｍ２１ , R Ｍ２２ , R Ｍ２３ , and R Ｍ２４ R each independently represents a hydrogen atom or an organic group. Ｍ２５ and R Ｍ２６ R each independently represents a hydrogen atom or an alkyl group. Ｍ２７ , R Ｍ２８ , R Ｍ２９ , and R Ｍ３０ R each independently represents a hydrogen atom or an organic group. Ｍ３１ and R Ｍ３２R each independently represents a hydrogen atom or an alkyl group. Ｍ３３ , R Ｍ３４ , R Ｍ３５ , and R Ｍ３６ R each independently represents a hydrogen atom or an organic group. Ｍ３７ , R Ｍ３８ , and R Ｍ３９ each independently represents a hydrogen atom or an alkyl group; and nx represents an integer of 1 or more and 20 or less.

[0075] R in the formula Ｍ２１ , R Ｍ２２ , R Ｍ２３ , and R Ｍ２４ R each independently represents a hydrogen atom or an organic group. The organic group here is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, still more preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and particularly preferably a methyl group. Ｍ２１ and R Ｍ２３ is preferably an alkyl group, and R Ｍ２２ and R Ｍ２４ is preferably a hydrogen atom. Ｍ２５ and R Ｍ２６ R each independently represents a hydrogen atom or an alkyl group, preferably an alkyl group. The alkyl group here is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, further preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and among these, a methyl group is particularly preferred. Ｍ２７ , R Ｍ２８ , R Ｍ２９ , and R Ｍ３０ R each independently represents a hydrogen atom or an organic group, preferably a hydrogen atom. The organic group here is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, still more preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and particularly preferably a methyl group. Ｍ３１ and R Ｍ３２R each independently represents a hydrogen atom or an alkyl group, preferably an alkyl group. The alkyl group here is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, further preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and among these, a methyl group is particularly preferred. Ｍ３３ , R Ｍ３４ , R Ｍ３５ , and R Ｍ３６ R each independently represents a hydrogen atom or an organic group. The organic group here is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, still more preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and particularly preferably a methyl group. Ｍ３３ and R Ｍ３６ is preferably a hydrogen atom, and R Ｍ３４ and R Ｍ３５ is preferably an alkyl group. Ｍ３７ , R Ｍ３８ , and R Ｍ３９ each independently represents a hydrogen atom or an alkyl group, with an alkyl group being preferred. The alkyl group here is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, further preferably a methyl group, an ethyl group, a propyl group, or a butyl group, with a methyl group being particularly preferred. nx represents an integer of 1 to 20. nx may also be an integer of 10 or less.

[0076] The compound represented by formula (M1-1) is preferably a compound represented by the following formula (M1-2): (In formula (M1-2), R Ｍ２１ , R Ｍ２２ , R Ｍ２３ , and R Ｍ２４ R each independently represents a hydrogen atom or an organic group. Ｍ２５ and R Ｍ２６ R each independently represents a hydrogen atom or an alkyl group. Ｍ２７ , R Ｍ２８ , R Ｍ２９ , and R Ｍ３０ R each independently represents a hydrogen atom or an organic group. Ｍ３１ and R Ｍ３２R each independently represents a hydrogen atom or an alkyl group. Ｍ３３ , R Ｍ３４ , R Ｍ３５ , and R Ｍ３６ R each independently represents a hydrogen atom or an organic group. Ｍ３７ , R Ｍ３８ , and R Ｍ３９ each independently represents a hydrogen atom or an alkyl group; and nx represents an integer of 1 or more and 20 or less.

[0077] In formula (M1-2), R Ｍ２１ , R Ｍ２２ , R Ｍ２３ , R Ｍ２４ , R Ｍ２５ , R Ｍ２６ , R Ｍ２７ , R Ｍ２８ , R Ｍ２９ , R Ｍ３０ , R Ｍ３１ , R Ｍ３２ , R Ｍ３３ , R Ｍ３４ , R Ｍ３５ , R Ｍ３６ , R Ｍ３７ , R Ｍ３８ , R Ｍ３９ , and nx are R in formula (M1-1), respectively. Ｍ２１ , R Ｍ２２ , R Ｍ２３ , R Ｍ２４ , R Ｍ２５ , R Ｍ２６ , R Ｍ２７ , R Ｍ２８ , R Ｍ２９ , R Ｍ３０ , R Ｍ３１ , R Ｍ３２ , R Ｍ３３ , R Ｍ３４ , R Ｍ３５ , R Ｍ３６ , R Ｍ３７ , R Ｍ３８ , R Ｍ３９ , and nx, and the preferred ranges are also the same.

[0078] The compound represented by formula (M1-1) is preferably a compound represented by the following formula (M1-3), and more preferably a compound represented by the following formula (M1-4). (In formula (M1-3), nx represents an integer of 1 or more and 20 or less.) nx may be an integer of 10 or less. (In formula (M1-4), nx represents an integer of 1 or more and 20 or less.) nx may be an integer of 10 or less.

[0079] The molecular weight of the compound represented by formula (M1) is preferably 500 or more, more preferably 600 or more, and even more preferably 700 or more. By making the molecular weight equal to or greater than the lower limit, the low dielectric properties and low water absorption of the resulting cured product (insulating layer) tend to be further improved. Furthermore, the molecular weight of the compound represented by formula (M1) is preferably 10,000 or less, more preferably 9,000 or less, even more preferably 7,000 or less, even more preferably 5,000 or less, and even more preferably 4,000 or less. By making the molecular weight equal to or less than the upper limit, the heat resistance and handleability of the resulting cured product (insulating layer) tend to be further improved.

[0080] The compound represented by formula (M1) preferably has a maleimide group equivalent of 50 g / eq. or more, more preferably 100 g / eq. or more, and even more preferably 200 g / eq. or more. The upper limit of the maleimide group equivalent is preferably 2000 g / eq. or less, more preferably 1000 g / eq. or less, and even more preferably 800 g / eq. or less. Here, the maleimide group equivalent represents the mass of the maleimide compound per equivalent of maleimide group. When the maleimide group equivalent of the compound represented by formula (M1) is within the above range, the resulting cured product (insulating layer) tends to have further improved low dielectric properties, low water absorption, heat resistance, and handleability.

[0081] The compound represented by formula (M1) preferably has a molecular weight distribution Mw / Mn calculated by gel permeation chromatography (GPC) measurement of 1.0 to 4.0, more preferably 1.1 to 3.8, even more preferably 1.2 to 3.6, and still more preferably 1.3 to 3.4. When the Mw / Mn of the compound represented by formula (M1) is within the above range, the resulting cured product (insulating layer) tends to have further improved low dielectric properties, low water absorbency, heat resistance, and handleability.

[0082] For other details of the compound represented by formula (M1), please refer to the descriptions in International Publication No. 2020-217679, the contents of which are incorporated herein by reference.

[0083] (In formula (M2), R ５４ each independently represents a hydrogen atom or a methyl group; n ４ represents an integer of 1 or more. ４ is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, even more preferably an integer of 1 to 3, still more preferably 1 or 2, and may be 1. In the compound represented by formula (M2), n ４ It may be, and is preferably, a mixture of compounds in which the other moieties are different. Furthermore, as described in the compound represented by formula (M0), it may be a mixture of compounds in which the other moieties are different.

[0084] (In formula (M3), R ５５ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group; n ５ represents an integer of 1 or more and 10 or less.) R ５５ are each independently preferably one selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, and a phenyl group, more preferably a hydrogen atom and / or a methyl group, and even more preferably a hydrogen atom. ５is preferably an integer of 1 or more and 5 or less, more preferably an integer of 1 to 3, and even more preferably 1 or 2. In the compound represented by formula (M3), n ５ It may be, and is preferably, a mixture of compounds in which the other moieties are different. Furthermore, as described in the compound represented by formula (M0), it may be a mixture of compounds in which the other moieties are different.

[0085] (In formula (M4), R ５６ each independently represents a hydrogen atom, a methyl group, or an ethyl group; R ５７ R each independently represents a hydrogen atom or a methyl group. ５６ are preferably each independently a methyl group or an ethyl group, and more preferably a methyl group and an ethyl group on each of the two benzene rings, and R ５７ is preferably a methyl group.

[0086] (In formula (M5), R ５８ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group; R ５９ each independently represents a hydrogen atom or a methyl group; n ６ represents an integer of 1 or more.) R ５８ are each independently preferably one selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, and a phenyl group, more preferably a hydrogen atom and / or a methyl group, and even more preferably a hydrogen atom. ５９ is preferably a methyl group. ６ is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, even more preferably an integer of 1 to 3, still more preferably 1 or 2, and may be 1. In the compound represented by formula (M5), n ６ It may be, and is preferably, a mixture of compounds in which the other moieties are different. Furthermore, as described in the compound represented by formula (M0), it may be a mixture of compounds in which the other moieties are different.

[0087] The maleimide compound (M6) is a compound having a structural unit represented by formula (M6) and maleimide groups at both ends of the molecular chain. (In formula (M6), R ６１ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms. ６２ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms. ６３ Each independently represents a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkenyl group having 2 to 16 carbon atoms. Each n independently represents an integer of 0 to 10.) For details of the maleimide compound (M6) and a production method thereof, please refer to paragraphs 0061 to 0066 of WO 2020 / 262577, the contents of which are incorporated herein by reference.

[0088] The maleimide compound (M7) is a maleimide compound obtained by reacting raw materials (1) with an aromatic amine compound (a1) having one to three alkyl groups on an aromatic ring, an aromatic divinyl compound (a2) having two ethenyl groups, and maleic anhydride. The maleimide compound (M7) is preferably a compound represented by formula (M7). (In the above formula (M7), R １ each independently represents an alkyl group having 1 to 10 carbon atoms; R ２ each independently represents an alkyl group, alkoxy group, or alkylthio group having 1 to 10 carbon atoms; an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms; a cycloalkyl group having 3 to 10 carbon atoms; a halogen atom; a hydroxyl group; or a mercapto group; ３ , R ４ , R ５ and R ６ each independently represents a hydrogen atom or a methyl group, and R ３ and R ４ one of which is a hydrogen atom and the other is a methyl group, and R ５ and R ６ one of which is a hydrogen atom and the other is a methyl group, １are each independently represented by the following formula (x): (In formula (x), R ７ and R ８ each independently represents a hydrogen atom or a methyl group, and R ７ and R ８ one of which is a hydrogen atom and the other is a methyl group, and R ９ each independently represents an alkyl group, alkoxy group, or alkylthio group having 1 to 10 carbon atoms; an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms; a cycloalkyl group having 3 to 10 carbon atoms; a halogen atom; a hydroxyl group; or a mercapto group, and t represents an integer of 0 to 4. １ X per benzene ring to which １ is the average number of substitutions, and represents a number from 0 to 4, p represents an integer from 1 to 3, q ​​represents an integer from 0 to 4, and k represents an integer from 1 to 100.

[0089] For details of the maleimide compound (M7) used in this embodiment, please refer to the description in Japanese Patent No. 7160151, the contents of which are incorporated herein by reference.

[0090] The maleimide compound (M8) is a maleimide compound having a hydrocarbon group in which eight or more atoms are linearly linked, and is preferably a compound represented by formula (M8): Such a bismaleimide compound (M8) tends to have a higher stress relaxation ability, and as a result, the thermal expansion coefficient of the obtained cured product tends to be lower, and the electrical properties such as the dielectric constant and the dielectric loss tangent tend to be more excellent. (In formula (M8), R １ and R ３ each independently represents a hydrocarbon group having 8 or more atoms linked in a linear chain, R ２ each independently represents a substituted or unsubstituted cyclic hydrocarbon group having 4 to 10 atoms constituting the ring, which may contain a heteroatom, and n represents a number from 0 to 10.

[0091] In formula (M8), R １ and R ３ is an octylene group, and R ２is preferably a cycloalkylene group having an alkyl group having 6 to 8 carbon atoms as a substituent.

[0092] For the maleimide compound (M8), the descriptions in paragraphs 0013 to 0022 of JP-A-2018-083893 and paragraphs 0011 to 0022 of JP-A-2018-090728 can be referred to, the contents of which are incorporated herein by reference.

[0093] The maleimide compound may be produced by a known method, or a commercially available product may be used. Examples of commercially available products include "BMI-80" manufactured by K.I. Chemical Industry Co., Ltd. as the compound represented by formula (M0), "NE-X-9470S" and "NE-X-9480S" manufactured by DIC Corporation as the compound represented by formula (M1), "BMI-2300" manufactured by Daiwa Kasei Kogyo Co., Ltd. as the compound represented by formula (M2), "MIR-3000-70MT" manufactured by Nippon Kayaku Co., Ltd. as the compound represented by formula (M3), and "MIR-3000-70MT" manufactured by Nippon Kayaku Co., Ltd. as the compound represented by formula (M4). Examples of compounds that can be used include "BMI-70" manufactured by K.I. Chemical Industry Co., Ltd. and "BMI-5100" manufactured by Daiwa Kasei Kogyo Co., Ltd.; examples of compounds represented by formula (M5) include "MIR-5000" manufactured by Nippon Kayaku Co., Ltd.; examples of maleimide compounds (M6) include "MIZ-001" manufactured by Nippon Kayaku Co., Ltd.; examples of maleimide compounds (M7) include "NE-X-9500" manufactured by DIC Corporation; examples of maleimide compounds (M8) include "SFR" manufactured by Resonac Inc., and "BMI-689", "BMI-3000", and "BMI-5000" manufactured by Designer Molecules Inc.

[0094] Examples of maleimide compounds other than those described above include N-phenylmaleimide, N-cyclohexylmaleimide, phenylmethane maleimide oligomers, m-phenylene bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene, and prepolymers thereof, prepolymers of these maleimides and amines, etc. In addition to the above, the compounds described in paragraphs 0051 to 0068 of WO 2020 / 262577 can be referenced, the contents of which are incorporated herein by reference.

[0095] When the resin composition contains a maleimide compound, the lower limit of the content is preferably 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. It may be 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 50 parts by mass or more, or 60 parts by mass or more. When the content of the maleimide compound is equal to or greater than the above-mentioned lower limit, the flame resistance of the resulting cured product (insulating layer) tends to be improved. Furthermore, the upper limit of the content of the maleimide compound is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. When the content of the maleimide compound is equal to or less than the above-mentioned upper limit, the metal foil peel strength and low water absorption tend to be improved. The resin composition in this embodiment may contain only one type of maleimide compound, or may contain two or more types of maleimide compounds. When two or more types are contained, the total amount is preferably within the above range.

[0096] <<Compound Having an Indane Skeleton with a Terminal Carbon-Carbon Unsaturated Double Bond>> The resin composition may contain a compound having an indane skeleton with a terminal carbon-carbon unsaturated double bond. An example of the compound having an indane skeleton with a terminal carbon-carbon unsaturated double bond is a resin represented by formula (T). (In formula (T), R is a group containing a structural unit represented by formula (Tx). R ｘ is a group containing a carbon-carbon unsaturated double bond. ｙ represents a hydrogen atom, a group containing an —O-carbon-carbon unsaturated double bond, or another group. y1 represents an integer of 1 to 4. Mb's each independently represent a hydroxyl group, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydroxyl group or a halogen atom. y represents an integer of 0 to 4. (In formula (Tx), n, o, and p represent the average number of structural units, n is a number greater than 0 and equal to or less than 20, o and p each independently represent a number from 0 to 20, and 1.0≦n+o+p≦20.0. Each Ma independently represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Each x independently represents an integer from 0 to 4. The structural units (a), (b), and (c) are each bonded to other structural units (a) to (c) at *, and the respective structural units may be bonded randomly.)

[0097] The compound having an indane skeleton with a terminal carbon-carbon unsaturated double bond may also be a resin whose main component is a structural unit derived from the compound represented by formula (DIP) and has a structure represented by formula (In-1) and / or formula (In-2). (In formula (DIP), each Ma independently represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and x represents an integer of 0 to 4.) (In formula (In-1), each Mb independently represents a hydroxyl group, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydroxyl group or a halogen atom. y represents an integer of 0 to 3. R ｘ is a group containing a carbon-carbon unsaturated double bond. * is a bonding site to other moieties. (In formula (In-2), each Ma independently represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom; x represents an integer of 0 to 3; each Mb independently represents a hydroxyl group, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydroxyl group or a halogen atom; y represents an integer of 0 to 4; R ｘ is a group containing a carbon-carbon unsaturated double bond. XP is the number of bonds coming out of the benzene ring and is an integer of 1 or 2. * is the bonding site to other moieties.)

[0098] For compounds having an indane skeleton having a terminal carbon-carbon unsaturated double bond, see paragraphs 0011 to 0025 of WO 2023 / 176766, paragraphs 0012 to 0033 of WO 2023 / 176764, paragraphs 0012 to 0033 of WO 2023 / 176763, and paragraphs 0026 to 0043 of WO 2023 / 176765, the contents of which are incorporated herein by reference.

[0099] <<Compound Having a Vinylene Group>> The resin composition may contain a compound having a vinylene group. Examples of compounds having a vinylene group include compounds containing one or more -CH=CH- groups in the molecule, and preferred are compounds containing one -CH=CH- group in the molecule. Furthermore, compounds having a vinylene group that also qualify as maleimide compounds are referred to as maleimide compounds. Specific examples of compounds having a vinylene group include preferred acenaphthylene and pyracylene, and more preferred is acenaphthylene. In this specification, compounds that also qualify as compounds having a vinylene group but are explicitly listed as components other than compounds having a vinylene group (e.g., curing accelerators), such as imidazole compounds described below, are not considered to be compounds having a vinylene group.

[0100] For details of the polymer having a structural unit represented by formula (V), (meth)allyl compound, (meth)acrylate compound, epoxy compound, phenol compound, oxetane resin, benzoxazine compound, arylcyclobutene compound, perfluorovinyl ether resin, polyamide compound, and polyimide compound, please refer to the descriptions in paragraphs 0075 to 0105 of WO 2023 / 171554 and the descriptions in paragraphs 0198 to 0200 of WO 2023 / 176765, the contents of which are incorporated herein by reference.

[0101] An example of the resin composition in this embodiment is one that is substantially free of epoxy compounds (including glycidyl compounds). "Substantially free of epoxy compounds" means that the content of epoxy compounds is less than 15% by mass of the resin solid content contained in the resin composition, preferably less than 10% by mass, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and may even be less than 1% by mass.

[0102] <Elastomer> The resin composition may contain an elastomer. In this embodiment, the elastomer is preferably a thermoplastic elastomer. The thermoplastic elastomer in this embodiment is not particularly limited, and examples thereof include at least one selected from the group consisting of polyisoprene, polybutadiene, styrene butadiene, butyl rubber, ethylene propylene rubber, styrene butadiene ethylene, styrene butadiene styrene, styrene isoprene styrene, styrene ethylene butylene styrene, styrene propylene styrene, styrene ethylene propylene styrene, fluororubber, silicone rubber, hydrogenated compounds thereof, alkyl compounds thereof, and copolymers thereof. Examples of elastomers include oligomers or polymers having a curable vinyl functional group and polybutadiene resins described in paragraphs 0044 and 0045 of JP 2019-194312 A, the contents of which are incorporated herein by reference.

[0103] The number-average molecular weight of the elastomer (preferably a thermoplastic elastomer) in this embodiment is preferably 1,000 or more. By setting the number-average molecular weight to 1,000 or more, the resulting cured product (insulating layer) tends to have better low dielectric properties (Dk and / or Df, particularly low dielectric loss tangent). The number-average molecular weight is preferably 1,500 or more, more preferably 2,000 or more, and may be 60,000 or more, 70,000 or more, or 80,000 or more depending on the application. The upper limit of the number-average molecular weight of the elastomer (preferably a thermoplastic elastomer) is preferably 400,000 or less, more preferably 350,000 or less, and even more preferably 300,000 or less. Setting the number-average molecular weight below the upper limit tends to improve the solubility of the elastomer component in the resin composition. When the resin composition contains two or more elastomers, it is preferable that the number-average molecular weight of the mixture thereof falls within the above range.

[0104] The elastomer used in this embodiment may be a resin containing a polybutadiene structure. The polybutadiene structure may be partially or completely hydrogenated. Specific examples include B-1000, B-2000, B-3000, BI-2000, and BI-3000 manufactured by Nippon Soda Co., Ltd., and Ricon 100, Ricon 130, Ricon 131, Ricon 142, Ricon 150, Ricon 181, and Ricon 184 manufactured by CRAY VALLEY.

[0105] The elastomer used in this embodiment may be a resin containing a poly(meth)acrylate structure, such as Teisan Resin manufactured by Nagase ChemteX Corporation, and ME-2000, W-197C, KG-15, and KG-3000 manufactured by Negami Chemical Industrial Co., Ltd.

[0106] The elastomer used in this embodiment may be a resin containing a polycarbonate structure. Resins containing a polycarbonate structure are sometimes referred to as "polycarbonate resins." Examples of such resins include carbonate resins without reactive groups, hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, urethane group-containing carbonate resins, and epoxy group-containing carbonate resins. Here, the term "reactive group" refers to a functional group capable of reacting with other components, such as a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an acid anhydride group, an isocyanate group, a urethane group, or an epoxy group. Specific examples of polycarbonate resins include FPC0220 and FPC2136 manufactured by Mitsubishi Gas Chemical Company, Inc., and T6002 and T6001 (polycarbonate diol) manufactured by Asahi Kasei Corporation.

[0107] The elastomer used in this embodiment is a resin containing a polysiloxane structure, such as SMP-2006, SMP-2003PGMEA, SMP-5005PGMEA, KR-510, and SMP-7014-3S manufactured by Shin-Etsu Silicones Co., Ltd.

[0108] The elastomer used in this embodiment may be a resin containing a polyalkylene structure and / or a polyalkyleneoxy structure. The polyalkyleneoxy structure is preferably a polyalkyleneoxy structure having 2 to 15 carbon atoms, more preferably a polyalkyleneoxy structure having 3 to 10 carbon atoms, and particularly preferably a polyalkyleneoxy structure having 5 to 6 carbon atoms. Specific examples of resins containing a polyalkylene structure and / or a polyalkyleneoxy structure include PTXG-1000 and PTXG-1800 manufactured by Asahi Kasei Corporation.

[0109] The elastomer used in this embodiment is a resin containing a polyisoprene structure, and specific examples include KL-610 and KL613 manufactured by Kuraray Co., Ltd.

[0110] The elastomer used in this embodiment may be a resin containing a polyisobutylene structure, such as SIBSTAR-073T (styrene-isobutylene-styrene triblock copolymer) and SIBSTAR-042D (styrene-isobutylene diblock copolymer), both manufactured by Kaneka Corporation.

[0111] In this embodiment, the thermoplastic elastomer is preferably a thermoplastic elastomer containing styrene monomer units and conjugated diene monomer units (hereinafter referred to as "thermoplastic elastomer (E)"). By using such a thermoplastic elastomer (E), the low dielectric properties (Dk and / or Df, particularly low dielectric loss tangent) of the resulting cured product (insulating layer) are more excellent.

[0112] The thermoplastic elastomer (E) in this embodiment contains a styrene monomer unit. The inclusion of the styrene monomer unit improves the solubility of the thermoplastic elastomer (E) in the resin composition. Examples of styrene monomers include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene (vinylstyrene), N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among these, styrene, α-methylstyrene, and p-methylstyrene are preferred from the viewpoints of availability and productivity. Of these, styrene is particularly preferred. The content of the styrene monomer unit in the thermoplastic elastomer (E) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 13% by mass, and even more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less, and even more preferably 40% by mass or less, of the total monomer units. If the content of styrene monomer units is 50% by mass or less, the adhesion and tackiness with the substrate, etc. will be better. Furthermore, if the content is 10% by mass or more, the adhesion can be suppressed, adhesive residue and stop marks are less likely to occur, and the adhesive surfaces tend to be easily peeled from each other, which is preferable. The thermoplastic elastomer (E) may contain only one type of styrene monomer unit, or may contain two or more types. When two or more types are contained, it is preferable that the total amount is within the above range. The method for measuring the content of styrene monomer units in the thermoplastic elastomer (E) of this embodiment can be found in International Publication No. 2017 / 126469, the contents of which are incorporated herein by reference. The same applies to the conjugated diene monomer units, etc., described below.

[0113] The thermoplastic elastomer (E) contains a conjugated diene monomer unit. The inclusion of the conjugated diene monomer unit improves the solubility of the thermoplastic elastomer (E) in a resin composition. The conjugated diene monomer is not particularly limited as long as it is a diolefin having one pair of conjugated double bonds. Examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and farnesene. 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. The thermoplastic elastomer (E) may contain only one type of conjugated diene monomer unit, or may contain two or more types.

[0114] In the thermoplastic elastomer (E), the mass ratio of the styrene monomer units to the conjugated diene monomer units (styrene monomer units / conjugated diene monomer units) is preferably in the range of 5 / 95 to 80 / 20, more preferably 7 / 93 to 77 / 23, and even more preferably 10 / 90 to 70 / 30. When the mass ratio of the styrene polymer units to the conjugated diene monomer units is in the range of 5 / 95 to 80 / 20, it is possible to suppress the increase in adhesion, maintain high adhesive strength, and improve the ease of peeling between adhesive surfaces.

[0115] The thermoplastic elastomer (E) may have all of its conjugated diene bonds hydrogenated, some of its conjugated diene bonds hydrogenated, or no conjugated diene bonds hydrogenated.

[0116] The thermoplastic elastomer (E) may or may not contain other monomer units in addition to the styrene monomer units and the conjugated diene monomer units. Examples of other monomer units include aromatic vinyl compound units other than styrene monomer units. The total of the styrene monomer units and the conjugated diene monomer units in the thermoplastic elastomer (E) is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more, of the total monomer units. As described above, the thermoplastic elastomer (E) may contain only one type of styrene monomer unit and one type of conjugated diene monomer unit, or two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0117] The thermoplastic elastomer (E) used in this embodiment may be a block polymer or a random polymer. It may also be a hydrogenated elastomer in which the conjugated diene monomer units are hydrogenated, an unhydrogenated elastomer in which no hydrogenation is performed, or a partially hydrogenated elastomer in which only a portion of the conjugated diene monomer units are hydrogenated. An unhydrogenated elastomer or a partially hydrogenated elastomer is preferred. In one embodiment of this embodiment, the thermoplastic elastomer (E) is a hydrogenated elastomer. Here, the term "hydrogenated elastomer" refers to, for example, a thermoplastic elastomer in which double bonds based on the conjugated diene monomer units in the thermoplastic elastomer are hydrogenated. This term encompasses elastomers with a hydrogenation rate (hydrogenation rate) of 100% or more, as well as elastomers with a hydrogenation rate of 80% or more. The hydrogenation rate of the hydrogenated elastomer is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more. In this embodiment, the hydrogenation rate is 1It is calculated from the results of H-NMR spectrum measurement. In one embodiment of this embodiment, the thermoplastic elastomer (E) is an unhydrogenated elastomer. Here, the unhydrogenated elastomer refers to an elastomer in which the proportion of hydrogenated double bonds based on conjugated diene monomer units in the elastomer, i.e., the hydrogenation rate (hydrogenation rate) is 20% or less. The hydrogenation rate is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. On the other hand, a partially hydrogenated elastomer refers to an elastomer in which some of the double bonds based on conjugated diene monomer units in the thermoplastic elastomer are hydrogenated, and typically refers to an elastomer in which the hydrogenation rate (hydrogenation rate) is less than 80% but more than 20%.

[0118] Examples of commercially available thermoplastic elastomers (E) used in this embodiment include SEPTON (registered trademark) 2104, V9461, and S8104 manufactured by Kuraray Co., Ltd., S.O.E. (registered trademark) S1606, S1613, S1609, and S1605 manufactured by Asahi Kasei Corporation, Tuftec (registered trademark) H1041, H1043, P2000, and MP10 manufactured by Asahi Kasei Corporation, and DYNARON (registered trademark) 9901P and TR2250 manufactured by JSR Corporation.

[0119] The elastomer used in this embodiment may also be a liquid diene. Liquid diene refers to a liquid elastomer containing a conjugated diene monomer unit. Examples of conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and farnesene. 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. Examples of liquid dienes used in this embodiment include liquid polybutadiene, liquid polyisoprene, modified liquid polybutadiene, modified liquid polyisoprene, liquid acrylonitrile-butadiene copolymer, and liquid styrene-butadiene copolymer. The number average molecular weight of the liquid diene is not particularly limited as long as it is liquid at 20°C, but is preferably 500 or more and 10,000 or less.

[0120] When the resin composition contains a thermoplastic elastomer (preferably, thermoplastic elastomer (E)), the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, still more preferably more than 15 parts by mass, and may even be 16 parts by mass or more, relative to 100 parts by mass of the resin solid content in the resin composition. By setting the content at or above the lower limit, the dielectric properties (low dielectric tangent) tend to be further improved. Furthermore, the upper limit of the content of the thermoplastic elastomer is preferably 45 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. By setting the content at or below the upper limit, the heat resistance tends to be further improved. The resin composition may contain only one type of thermoplastic elastomer, or may contain two or more types. When two or more types are contained, the total amount preferably falls within the above range.

[0121] <Styrene-Based Oligomer> The resin composition can also contain a styrene-based oligomer to improve low dielectric constant and low dielectric loss tangent. However, components that also fall under the category of other components explicitly described herein and also fall under the category of styrene-based oligomers are classified as "other components." The styrene-based oligomer according to this embodiment is a compound obtained by polymerizing at least one selected from the group consisting of styrene, styrene derivatives (α-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, etc.), and vinyltoluene, and has a number-average molecular weight of 178 to 1600, an average number of aromatic rings of 2 to 14, a total amount of the 2 to 14 aromatic rings of 50% by mass or more, and a boiling point of 300°C or higher, preferably one without a branched structure. Styrene-based oligomers are typically thermoplastic. Furthermore, styrene-based oligomers do not have polymerizable carbon-carbon unsaturated double bonds. However, compounds that fall under the category of styrene-based oligomers and also fall under the category of thermosetting compounds are considered to be thermosetting compounds.

[0122] For details of the styrene-based oligomer, please refer to the descriptions in paragraphs 0065 to 0067 of WO 2019 / 230945 and paragraphs 0253 to 0245 of WO 2023 / 176765, the contents of which are incorporated herein by reference.

[0123] When the resin composition contains a styrene-based oligomer, the content thereof is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and even optionally 5 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. By setting the content at or above the lower limit, the low dielectric properties (Dk and / or Df) of the resulting cured product (insulating layer) tend to be further improved. Furthermore, the upper limit of the content of the styrene-based oligomer is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. By setting the content at or below the upper limit, the heat resistance tends to be further improved. Furthermore, the low dielectric properties (Dk and / or Df) and chemical resistance of the resulting cured product (insulating layer) tend to be further improved. The resin composition may contain only one type of styrene-based oligomer, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0124] <Filler> The resin composition preferably contains a filler. By including a filler, the dielectric properties (low dielectric constant, low dielectric loss tangent, etc.), flame resistance, low thermal expansion, and other physical properties of the resin composition and its cured product can be further improved. Furthermore, the filler used in this embodiment preferably has excellent low dielectric properties. For example, the filler used in this embodiment preferably has a relative dielectric constant (Dk) of 8.0 or less, more preferably 6.0 or less, and even more preferably 4.0 or less at a frequency of 10 GHz, as measured according to a cavity resonator perturbation method. Furthermore, a practical lower limit of the relative dielectric constant is, for example, 2.0 or more. Furthermore, the filler used in this embodiment preferably has a dielectric loss tangent (Df) of 0.05 or less, more preferably 0.01 or less at a frequency of 10 GHz, as measured according to a cavity resonator perturbation method. Furthermore, a practical lower limit of the dielectric loss tangent is, for example, 0.0001 or more.

[0125] The filler used in this embodiment is not particularly limited in type, and can suitably be used as the one generally used in this industry.Specifically, natural silica, fused silica, synthetic silica, amorphous silica, aerosil, hollow silica, etc. silica, alumina, white carbon, titanium white, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, etc. metal oxide, zinc borate, zinc stannate, forsterite, barium titanate, strontium titanate, calcium titanate, etc. composite oxide, boron nitride, aggregated boron nitride, silicon nitride, aluminum nitride, etc. nitride, aluminum hydroxide, aluminum hydroxide heat treatment product (aluminum hydroxide is heat treated, and part of crystal water is reduced), boehmite, magnesium hydroxide, etc. metal hydroxide (including hydrate), molybdenum oxide, and molybdenum compounds such as zinc molybdate, barium sulfate, clay, kaolin, talc, calcined clay, calcined kaolin, calcined talc, mica, E-glass, A-glass, NE-glass, NER-glass, C-glass, L-glass, D-glass, S-glass, M-glass G20, short glass fiber (including fine glass powders such as E-glass, T-glass, D-glass, S-glass, and Q-glass), hollow glass, and spherical glass. In addition, organic fillers such as styrene-type, butadiene-type, and acrylic-type rubber powders, core-shell-type rubber powders, silicone resin powders, silicone rubber powders, and silicone composite powders can be used. In this embodiment, the filler preferably contains an inorganic filler, more preferably one or more selected from the group consisting of silica, aluminum hydroxide, aluminum nitride, boron nitride, forsterite, titanium oxide, barium titanate, strontium titanate, and calcium titanate, and from the viewpoint of low dielectric properties, more preferably one or more selected from the group consisting of silica and aluminum hydroxide, and even more preferably silica. By containing these inorganic fillers, the properties of the cured product of the resin composition, such as heat resistance, dielectric properties, thermal expansion properties, dimensional stability, and flame retardancy, are further improved.

[0126] The content of the filler in the resin composition can be appropriately set depending on the desired properties and is not particularly limited. However, it is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 80 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. By setting the content of the filler to the above lower limit or more, heat resistance, low thermal expansion, and dielectric loss tangent tend to be further improved. Furthermore, the upper limit of the content of the filler is preferably 1,000 parts by mass or less, more preferably 500 parts by mass or less, even more preferably 300 parts by mass or less, even more preferably 250 parts by mass or less, and may be 200 parts by mass or less, or 120 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. By setting the content of the filler to the above upper limit or less, moldability tends to be further improved. In the resin composition, as an example of a preferred embodiment, the content of the filler is 30% by mass to 90% by mass of the components excluding the solvent. The resin composition may contain only one type of filler, or may contain two or more types. When two or more types are contained, it is preferable that the total amount is in the above range.

[0127] When a filler, particularly an inorganic filler, is used in the resin composition, the resin composition may further contain a silane coupling agent. The inclusion of a silane coupling agent tends to further improve the dispersibility of the filler and the adhesive strength between the resin component and the filler and the substrate described below. The silane coupling agent is not particularly limited, and examples thereof include silane coupling agents generally used in the surface treatment of inorganic substances, such as aminosilane compounds (e.g., γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, etc.), epoxysilane compounds (e.g., γ-glycidoxypropyltrimethoxysilane, etc.), vinylsilane compounds (e.g., vinyltrimethoxysilane, etc.), styrylsilane compounds (e.g., p-styryltrimethoxysilane, etc.), acrylicsilane compounds (e.g., γ-acryloxypropyltrimethoxysilane, etc.), cationic silane compounds (e.g., N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, etc.), phenylsilane compounds (e.g., phenyltrimethoxysilane, etc.), etc. Silane coupling agents may be used alone or in combination of two or more. The content of the silane coupling agent is not particularly limited, but may be 0.1 to 5.0 parts by mass per 100 parts by mass of the resin solid content in the resin composition.

[0128] <Flame Retardant> The resin composition may contain a flame retardant other than the phosphate ester compound. Examples of the flame retardant include halogen-based flame retardants, inorganic flame retardants, and silicone-based flame retardants.

[0129] <Active ester compound> The resin composition may contain an active ester compound. The active ester compound is not particularly limited, and for example, the description in paragraphs 0064 to 0066 of WO 2021 / 172317 can be referred to, the contents of which are incorporated herein by reference.

[0130] When the resin composition contains an active ester compound, the amount is preferably 1 part by mass or more and preferably 50 parts by mass or less per 100 parts by mass of the resin solid content in the resin composition. The resin composition in this embodiment may contain only one type of active ester compound, or may contain two or more types. When two or more types are contained, it is preferable that the total amount is in the above range. Furthermore, the resin composition in this embodiment may be configured to be substantially free of an active ester compound. "Substantially free" means that the content of the active ester compound is less than 1 part by mass, preferably less than 0.1 parts by mass, and more preferably less than 0.01 parts by mass per 100 parts by mass of the resin solid content in the resin composition.

[0131] <Dispersant> The resin composition may contain a dispersant. As the dispersant, those generally used for paints can be suitably used, and the type is not particularly limited. As the dispersant, a copolymer-based wetting dispersant is preferably used, and specific examples thereof include DISPERBYK (registered trademark)-110, 111, 161, 180, 2009, 2152, 2155, BYK (registered trademark)-W996, W9010, W903, and W940 manufactured by BYK Japan K.K.

[0132] When the resin composition contains a dispersant, the lower limit of the content is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and may be 0.3 parts by mass or more, relative to 100 parts by mass of the resin solid content in the resin composition. The upper limit of the content of the dispersant is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. The dispersants can be used alone or in combination of two or more. When two or more types are used, the total amount falls within the above range.

[0133] <Curing Accelerator> The resin composition may further contain a curing accelerator. The curing accelerator is not particularly limited, and examples thereof include imidazoles such as 2-ethyl-4-methylimidazole and triphenylimidazole; organic peroxides such as benzoyl peroxide, bis(1-methyl-1-phenylethyl)peroxide, di-t-butyl peroxide, lauroyl peroxide, acetyl peroxide, parachlorobenzoyl peroxide, di-tert-butyl-di-perphthalate, α,α'-di(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3; azo compounds such as azobisnitriles (e.g., azobisisobutyronitrile); N,N-dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethyltoluidine, 2-N-ethylanilinoethanol, and thiazolinone; tertiary amines such as tri-n-butylamine, pyridine, quinoline, N-methylmorpholine, triethanolamine, triethylenediamine, tetramethylbutanediamine, and N-methylpiperidine; phenols such as phenol, xylenol, cresol, resorcinol, and catechol; high-temperature decomposition type radical generators such as 2,3-dimethyl-2,3-diphenylbutane; organic metal salts such as lead naphthenate, lead stearate, zinc naphthenate, zinc octylate, manganese octylate, tin oleate, dibutyltin maleate, manganese naphthenate, cobalt naphthenate, and iron acetylacetonate; compounds obtained by dissolving these organic metal salts in hydroxyl group-containing compounds such as phenol and bisphenol; inorganic metal salts such as tin chloride, zinc chloride, and aluminum chloride; and organic tin compounds such as dioctyltin oxide, other alkyltins, and alkyltin oxides. The curing accelerator is preferably one or more selected from the group consisting of imidazoles, organic peroxides, and organic metal salts, and it is more preferable to use a combination of both an imidazole and an organic metal salt, or an imidazole and an organic peroxide.

[0134] When the resin composition contains a curing accelerator, the lower limit of the content is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition. The upper limit of the curing accelerator content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, even more preferably 1.5 parts by mass or less, and may be 1.0 parts by mass or less, 0.8 parts by mass or less, or 0.7 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition. One type of curing accelerator can be used alone, or two or more types can be used in combination. When two or more types are used, the total amount falls within the above range. In addition, in this embodiment, the resin composition may be configured to be substantially free of polymerization initiators such as organic peroxides and azo compounds. "Substantially free" means that the content of the polymerization initiator is less than 0.1 parts by mass per 100 parts by mass of the resin solid content in the resin composition. In this embodiment, the resin composition may be configured to be substantially free of a curing accelerator. "Substantially free" means that the content of the curing accelerator is less than 0.1 parts by mass per 100 parts by mass of the resin solid content in the resin composition.

[0135] <Solvent> The resin composition may contain a solvent, and preferably contains an organic solvent. When a solvent is contained, the resin composition is in a form (solution or varnish) in which at least a portion, preferably all, of the various resin solid components described above are dissolved or compatible in the solvent. The solvent is not particularly limited as long as it is a polar organic solvent or a non-polar organic solvent that can dissolve or compatible at least a portion, preferably all, of the various resin solid components described above. Examples of polar organic solvents include ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclohexanone, etc.), cellosolves (e.g., propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc.), esters (e.g., ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate, methyl methoxypropionate, methyl hydroxyisobutyrate, etc.), and amides (e.g., dimethoxyacetamide, dimethylformamide, etc.). Examples of non-polar organic solvents include aromatic hydrocarbons (e.g., toluene, xylene, etc.). The solvents can be used alone or in combination of two or more.

[0136] <Other Resin Additive Components> In addition to the above components, the resin composition may contain various polymeric compounds such as thermoplastic resin oligomers and various additives. Examples of additives include ultraviolet absorbers, antioxidants, photopolymerization initiators, fluorescent brighteners, photosensitizers, colorants (dyes, pigments), thickeners, flow control agents, lubricants, antifoaming agents, leveling agents, gloss agents, and polymerization inhibitors such as quinones, phenols, nitroso, and hydroxyamines. These additives may be used alone or in combination of two or more. The resin composition may or may not contain a non-metallic organic dye. The content of the non-metallic organic dye in the resin composition is preferably less than 2 parts by mass, more preferably less than 1 part by mass, even more preferably less than 0.5 parts by mass, even more preferably less than 0.3 parts by mass, and even more preferably less than 0.1 parts by mass, per 100 parts by mass of resin solids.

[0137] The resin solid content contained in the resin composition is such that the total amount of components selected from a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, a cyanate ester compound, a maleimide compound (preferably a maleimide compound having no unshared electron pair), and an elastomer accounts for preferably 80 mass % or more of the total, more preferably 85 mass % or more, even more preferably 90 mass % or more, still more preferably 95 mass % or more, even more preferably 97 mass % or more, and 100 mass % or less.

[0138] The resin composition preferably has a low dielectric constant (Dk) and dielectric loss tangent (Df) when cured. Specifically, the dielectric constant (Dk) at a frequency of 10 GHz measured according to a cavity resonator perturbation method when the resin composition is molded into a cured plate having a thickness of 1.0 mm is preferably 2.70 or less, more preferably 2.60 or less, and even more preferably 2.50 or less. The lower limit of the dielectric constant (Dk) is not particularly specified, but a practical value is, for example, 1 or more. Furthermore, the dielectric loss tangent (Df) at a frequency of 10 GHz measured according to a cavity resonator perturbation method when the resin composition is molded into a cured plate having a thickness of 1.0 mm is preferably 0.0030 or less, more preferably 0.0025 or less. The lower limit of the dielectric loss tangent (Df) is not particularly specified, but a practical value is, for example, 0.0001 or more. More specifically, the relative dielectric constant (Dk) and dielectric loss tangent (Df) of the cured sheet are measured by the method described in the examples below.

[0139] <Configuration of Resin Composition-Containing Layer> The resin composition-containing layer of the multilayer body of the first embodiment of this embodiment is formed from a resin composition. The resin composition-containing layer may contain a resin solid content, a solvent, and a filler. The resin composition-containing layer may also contain only a resin solid content, or only a resin solid content and a filler. Furthermore, as will be described in detail later, it may also contain a substrate.

[0140] A first example of the resin composition-containing layer is a resin sheet formed from a resin composition. The resin sheet here does not include a substrate. The thickness of the resin sheet is preferably 3.0 μm or more, more preferably 5.0 μm or more, and may be 10 μm or more. The thickness of the resin sheet is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. By making the thickness equal to or greater than the lower limit, the effect of ensuring interlayer insulation tends to be further improved. Furthermore, by making the thickness equal to or less than the upper limit, the thickness of the product tends to be reduced. In the first example of the resin composition-containing layer, it is preferable that only resin solids and a filler are included. However, it goes without saying that residual solvents, etc. are not actively excluded.

[0141] A second example of the resin composition-containing layer is a prepreg formed from a substrate and the resin composition. The prepreg is formed from a substrate (prepreg substrate) and the resin composition. The prepreg can be obtained, for example, by applying the resin composition to the substrate (e.g., by impregnation and / or coating) and then semi-curing by heating (e.g., by drying at 120 to 220°C for 2 to 15 minutes). In this case, the amount of the resin composition attached to the substrate, i.e., the amount of the resin composition (including the filler) relative to the total amount of the semi-cured prepreg, is preferably in the range of 20 to 99% by mass, more preferably in the range of 20 to 80% by mass.

[0142] The substrate is not particularly limited as long as it is a substrate used in various printed wiring board materials. Examples of the substrate material include glass fibers (e.g., E-glass, D-glass, L-glass, S-glass, T-glass, Q-glass, UN-glass, NE-glass, NER-glass, spherical glass, etc.), inorganic fibers other than glass (e.g., quartz, etc.), and organic fibers (e.g., polyimide, polyamide, polyester, liquid crystal polyester, polytetrafluoroethylene, etc.). The form of the substrate is not particularly limited, and examples include woven fabric, nonwoven fabric, roving, chopped strand mat, surfacing mat, etc. These substrates may be used alone or in combination of two or more types. Among these substrates, glass cloth is preferred. The glass cloth has a thickness of 200 μm or less and a mass of 250 g / m ２ The following glass woven fabrics are preferred, and from the viewpoint of moisture absorption and heat resistance, glass cloth surface-treated with a silane coupling agent such as epoxy silane or amino silane is preferred. From the viewpoint of electrical properties, low-dielectric glass cloth made of glass fibers exhibiting a low relative dielectric constant and low dielectric dissipation factor, such as L-glass, NE-glass, NER-glass, or Q-glass, is more preferred. Examples of substrates with a low relative dielectric constant include substrates with a relative dielectric constant of 5.0 or less (preferably, 3.0 to 4.9). Examples of substrates with a low dielectric dissipation factor include substrates with a dielectric dissipation factor of 0.006 or less (preferably, 0.001 to 0.005). The relative dielectric constant and dielectric dissipation factor are values ​​measured at a frequency of 10 GHz using a perturbation method cavity resonator.

[0143] <Insulating Layer> The insulating layer in the multilayer body of this embodiment is an insulating layer that is a cured product of the resin composition-containing layer. The insulating layer is obtained by heating the above-mentioned resin composition-containing layer typically at 180°C or higher, preferably 200°C or higher, and typically at 300°C or lower, preferably 250°C or lower. The thickness of the insulating layer is preferably 5 μm or higher, more preferably 10 μm or higher, and may be 20 μm or higher depending on the application. The upper limit of the thickness of the insulating layer is preferably 200 μm or lower, more preferably 150 μm or lower, and even more preferably 100 μm or lower, and may be 50 μm or lower, or 30 μm or lower depending on the application. The thickness of the insulating layer can be adjusted by laminating one or more resin sheets and / or prepregs as the above-mentioned resin composition-containing layer depending on the desired application. Note that the thickness of the insulating layer refers to the thickness including the substrate, for example, in the case of a cured product of a resin composition-containing layer (e.g., a prepreg) in which a substrate is impregnated with the resin composition.

[0144] The insulating layer, which is a cured product of the resin composition-containing layer, preferably has a high glass transition temperature. Specifically, the glass transition temperature is preferably 233°C or higher, more preferably 240°C or higher, even more preferably 245°C or higher, and even more preferably 250°C or higher, with 300°C or lower being practical. The glass transition temperature is determined by measuring dynamic viscoelasticity using a dynamic viscoelasticity measuring device (DMA) in accordance with JIS-K7244-5:1999 (Plastics - Test methods for dynamic mechanical properties - Part 5: Bending vibration - Non-resonance method) under conditions of a starting temperature of 30°C, an ending temperature of 350°C, a heating rate of 10°C / min, and a measurement frequency of 10 Hz. The maximum value of the dynamic elastic modulus (Loss Modulus) obtained at this time is taken as the glass transition temperature. The dynamic viscoelasticity measuring device used is a DMA Q-800 manufactured by TA Instruments.

[0145] <Inner Layer Circuit Board> The multilayer body of this embodiment may further include an inner layer circuit board. The inner layer circuit board is provided so that the resin composition-containing layer is in contact with the inner layer circuit board, or so that the insulating layer is in contact with the inner layer circuit board. The inner layer circuit serves as a conductor circuit.

[0146] <Method for Producing a Printed Wiring Board> Next, a method for producing a printed wiring board using the multilayer body of this embodiment will be described. The method for producing a printed wiring board using the multilayer body of this embodiment is not particularly limited, and can be obtained, for example, by the following method. The following description will be made with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram of an example of a multilayer body 1 of this embodiment, which includes an inner layer circuit board 3 in addition to a resin composition-containing layer 2, and the resin composition-containing layer 2 is provided so as to contact the inner layer circuit board 3. Also, in FIG. 1, a metal foil 4 is provided on the surface of the resin composition-containing layer 2 that is not in contact with the inner layer circuit board 3. The resin composition-containing layer 2 is typically processed under heat and pressure to form a cured insulating layer (reference numeral 21 in FIG. 2, described below). In this embodiment, the surface roughness Rz of the metal foil 4 is small, at 2 μm or less, so that the roughness transferred to the surface of the insulating layer 21 obtained from the specified resin composition is small or non-existent. Furthermore, since the resin composition-containing layer 2 is formed from the above-mentioned specified resin composition, as a result, when the resin composition-containing layer 2 is used as the insulating layer 21, it has high adhesion to the electroless plating layer (reference numeral 22 in Figure 2 described later).

[0147] The method for producing a printed wiring board of this embodiment includes removing the metal foil from the second multilayer body of this embodiment, performing an electroless plating process on the surface of the insulating layer from which the metal foil has been removed to form an electroless plated layer, forming a desired resist pattern on the surface of the electroless plated layer, performing a plating process on the surface on which the desired resist pattern has been formed to form a second plated layer, removing the resist pattern, and etching a portion of the electroless plated layer to expose the insulating layer and form a desired wiring pattern. Below, details of the method for producing a printed wiring board using the multilayer body shown in Figure 1 will be described with reference to Figure 2. It goes without saying that the method for producing a printed wiring board of this embodiment is not limited to that shown in Figure 2.

[0148] (1) Removing the Metal Foil of the Second Multilayer Body of the Present Embodiment (1) in Fig. 2 shows a process of removing all of the metal foil 4 (not shown) of the multilayer body 1 (the second multilayer body having an insulating layer that is a cured product of the resin composition-containing layer) shown in Fig. 1 by etching or the like. The method for etching away the metal foil is not particularly limited, and known methods such as methods using ferric chloride, copper chloride, or ammonium persulfate solution can be used.

[0149] (2) Electroless plating is performed on the surface of the insulating layer from which the metal foil has been removed to form an electroless plated layer. (2) in Figure 2 illustrates the process of performing electroless plating to form an electroless plated layer 22. In this embodiment, even if the electroless plated layer 22 is formed without roughening the insulating layer 21, the electroless plated layer 22, which has excellent adhesion to the insulating layer 21, and thus the second plated layer 24, which will be described in detail later, can be formed. This simplifies the manufacturing process and significantly reduces the environmental impact in the printed wiring board manufacturing method. In this embodiment, drying is preferably performed after the electroless plating to remove any moisture contained therein. As for drying conditions after the electroless plating, any drying conditions sufficient to remove moisture are effective, but heating at 100 to 170°C for 1 to 5 hours is more preferred. Such drying not only removes moisture but also further improves adhesion between the insulating layer and the metal layer (plated layer and / or wiring pattern). The electroless plating is preferably copper electroless plating.

[0150] (3) Forming a desired resist pattern on the surface of the electroless plated layer (3) in FIG. 2 shows a step of forming a desired resist pattern 23 on the surface of the electroless plated layer 22. For example, a photoresist can be laminated on the surface of the electroless plated layer 22, and the photoresist can be exposed and developed to form the resist pattern 23. The resist pattern 23 can be formed according to a known method. For information on the formation of the resist pattern 23, please refer to the description in JP 2020-136646 A, the contents of which are incorporated herein by reference.

[0151] (4) Plating the surface on which the desired resist pattern 23 has been formed to form a second plating layer. (4) in Fig. 2 shows the step of plating the surface on which the desired resist pattern 23 has been formed to form a second plating layer 24. The second plating layer 24 may be formed by either electroless plating or electrolytic plating, but is preferably formed by electrolytic plating. Copper plating is preferred.

[0152] (5) Removing the Resist Pattern (5) in Figure 2 shows a step of removing the resist pattern 23. The resist pattern 23 can be removed by a known method. For the removal of the resist pattern 23, the description in JP 2020-136646 A can be referred to, and the contents thereof are incorporated herein by reference.

[0153] (6) Etching a portion of the electroless plated layer to expose the insulating layer and form a desired wiring pattern (6) in Figure 2 shows a process of etching a portion of the electroless plated layer 22 to expose a portion of the insulating layer 21 and form a desired wiring pattern 25. After forming the wiring pattern 25, heat treatment at 150 to 200°C for 20 to 90 minutes can be performed to further improve and stabilize the adhesion between the wiring pattern and the insulating layer.

[0154] In this embodiment, the surface roughness of the metal foil 4 is particularly reduced, reducing or eliminating the roughness transferred to the surface of the insulating layer 21 obtained from the above-mentioned predetermined resin composition, and forming the electroless plated layer 22 by electroless plating. This improves adhesion between the second plated layer 24, and therefore the wiring pattern 25, and the insulating layer 21 compared to conventional methods. Furthermore, unnecessary portions of the electroless plated layer 22 can be removed more precisely by etching. As a result, a wiring pattern 25 with a small line / space ratio (L / S ratio) can be formed, and excellent adhesion to the insulating layer 21 can also be achieved.

[0155] The second multilayer body of this embodiment preferably has a peel strength (ESAP peel) of 0.35 kN / m or more, more preferably 0.40 kN / m or more, even more preferably 0.45 kN / m or more, and may have a peel strength of 1.0 kN / m or less, after removing the metal foil from the multilayer body and subjecting the surface of the insulating layer to electroless plating and electrolytic plating. A peel strength of 0.40 kN / m or more is particularly advantageous in enabling the formation of finer wiring patterns. The peel strength (ESAP peel) is measured by the method described in the Examples. The line width L of the resulting wiring pattern is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and even more preferably 2 μm or less, and is substantially 0.1 μm or more. The space width S of the wiring pattern is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and even more preferably 2 μm or less, and is substantially 0.1 μm or more. Furthermore, it is preferable that both the line width L and the space width S satisfy the above ranges. In particular, the multilayer body of this embodiment is excellent in that it can form a fine wiring pattern in which both L and S are 2 μm or less.

[0156] <Uses> The multilayer body of this embodiment, particularly the first multilayer body (a multilayer body including a metal foil and a resin composition-containing layer) is suitably used as a material for printed wiring boards. In particular, a cured product of the resin composition layer is suitably used as an insulating layer of a printed wiring board.

[0157] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0158] <Measurement of Weight-Average Molecular Weight and Number-Average Molecular Weight> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of compounds (including resins) were measured by gel permeation chromatography (GPC) using a liquid pump (Shimadzu Corporation, LC-20AD), a differential refractive index detector (Shimadzu Corporation, RID-20A), and GPC columns (Showa Denko K.K., GPC KF-801, 802, 803, 804), with tetrahydrofuran as the solvent, a flow rate of 1.0 mL / min, and a column temperature of 40°C, using a calibration curve prepared using monodisperse polystyrene.

[0159] Synthesis Example 1: Synthesis of naphthol aralkyl cyanate ester compound (SNCN) 300 g (1.28 mol in terms of OH groups) of 1-naphthol aralkyl resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.) and 194.6 g (1.92 mol) of triethylamine (1.5 mol per mol of hydroxy groups) were dissolved in 1,800 g of dichloromethane, and the resulting solution was designated Solution 1. 125.9 g (2.05 mol) of cyanogen chloride (1.6 mol per mol of hydroxy groups), 293.8 g of dichloromethane, 194.5 g (1.92 mol) of 36% hydrochloric acid (1.5 mol per mol of hydroxy groups), and 1,205.9 g of water were added thereto with stirring over 30 minutes while maintaining the liquid temperature between −2° C. and −0.5° C. After the addition of Solution 1 was completed, the mixture was stirred at the same temperature for 30 minutes, and then a solution (Solution 2) prepared by dissolving 65 g (0.64 mol) of triethylamine (0.5 mol per mol of hydroxyl groups) in 65 g of dichloromethane was added over 10 minutes. After the addition of Solution 2 was completed, the mixture was stirred at the same temperature for 30 minutes to complete the reaction. The reaction solution was then allowed to stand, and the organic and aqueous phases were separated. The resulting organic phase was washed five times with 1,300 g of water. The electrical conductivity of the wastewater from the fifth water wash was 5 μS / cm, confirming that the ionic compounds were sufficiently removed by washing with water. The organic phase after water washing was concentrated under reduced pressure and finally concentrated to dryness at 90°C for 1 hour, yielding 331 g of the desired naphthol aralkyl cyanate ester compound (SNCN) (orange viscous substance). The weight-average molecular weight of the resulting SNCN was 600. The IR spectrum of SNCN measured at 2250 cm －１The absorption of the cyanate ester group was observed, and the absorption of the hydroxyl group was not observed.

[0160] Synthesis Example 2: Synthesis of polyphenylene ether compound having terminal carbon-carbon unsaturated double bonds Synthesis of bifunctional phenylene ether oligomer CuBr was placed in a vertical reactor equipped with a stirrer, a thermometer, an air inlet tube, and a baffle. ２ 0.33 g (1.5 mmol) of copper bromide, 0.63 g (3.7 mmol) of N,N'-di-t-butylethylenediamine, 6.95 g (69 mmol), 670 g of toluene, and 320 g of methanol were charged and dissolved by stirring at a reaction temperature of 40°C. Separately, in advance, in a separate vessel, 46.2 g (171 mmol) of 2,2',3,3',5,5'-hexamethyl-(1,1'-biphenyl)-4,4'-diol, 129.5 g (1,060 mmol) of 2,6-dimethylphenol, and CuBr ２ 0.33 g (1.5 mmol) of copper bromide, 0.63 g (3.7 mmol) of N,N'-di-t-butylethylenediamine, 6.95 g (69 mmol) of n-butyldimethylamine, 440 g of toluene, and 170 g of methanol were charged and dissolved with stirring at a reaction temperature of 40°C. Subsequently, while bubbling a mixed gas adjusted to an oxygen concentration of 8% by mixing nitrogen and air into the mixed solution in the polymerization tank, the mixed solution in the dropping tank was added dropwise over 280 minutes and stirred. After completion of the dropwise addition, 700 g of water in which 7.1 g (16 mmol) of tetrasodium ethylenediaminetetraacetate had been dissolved was added to terminate the reaction. The aqueous layer and the organic layer were separated, and the organic layer was washed with a 1 M aqueous hydrochloric acid solution and then with pure water. The resulting solution was concentrated to 50% by mass using an evaporator, yielding 340 g of phenylene ether resin toluene solution A. The number average molecular weight as calculated on a polystyrene basis by the GPC method was 985, the weight average molecular weight as calculated on a polystyrene basis by the GPC method was 1090, and the hydroxyl equivalent was 478 g / eq.

[0161] <<Synthesis of Polyphenylene Ether Compound Having Terminal Carbon-Carbon Unsaturated Double Bonds>> A reactor equipped with a stirrer, thermometer, and reflux condenser was charged with 300 g of the toluene solution A of the phenylene ether resin obtained above, 57.5 g (0.38 mol) of vinylbenzyl chloride (manufactured by AGC Seimi Chemical Co., Ltd., "CMS-P"), 1,200 g of methylene chloride, 5 g (0.037 mol) of benzyldimethylamine, 70 g of pure water, and 63 g of a 30.5% by mass aqueous NaOH solution, and the mixture was stirred at a reaction temperature of 40°C. After stirring for 24 hours, the organic layer was washed with a 1 M aqueous hydrochloric acid solution and then with pure water. The resulting solution was concentrated and added dropwise to methanol to solidify. The solid was collected by filtration and dried in vacuo to obtain 178 g of a polyphenylene ether compound primarily composed of a compound represented by formula (OP-15). The number average molecular weight (GPC) was 1,200 in terms of polystyrene, the weight average molecular weight (GPC) was 1,840 in terms of polystyrene, the vinyl double bond equivalent was 620 g / eq., and the hydroxyl equivalent was 48,500 g / eq.

[0162] Example 1 37.5 parts by mass of the maleimide compound (ma) shown below (NE-X-9470S manufactured by DIC Corporation, functional group equivalent (maleimide group equivalent) 450 g / eq., compound represented by formula (M1)), 37.5 parts by mass of the maleimide compound (mb) (biphenylaralkyl maleimide, compound represented by formula (M3), MIR-3000 manufactured by Nippon Kayaku Co., Ltd.), 5.0 parts by mass of the cyanate ester compound obtained in Synthesis Example 1 above (SNCN, solid at 23°C), and 20.0 parts by mass of a thermoplastic elastomer (SBS, TR2250 manufactured by JSR Corporation) were blended together, and the blend was diluted with methyl ethyl ketone to a solids content of 65% by mass to obtain a varnish. The blend amounts of each component shown above are values ​​based on the solids content.

[0163] Maleimide compound (ma) Maleimide compound (mb)

[0164] <Production of a 1.0 mm Thick Cured Plate> A resin composition powder was obtained by evaporating and distilling off the solvent from the resulting varnish. The resin composition powder was filled into a mold with a side length of 100 mm and a thickness of 1.0 mm, and ultra-thin copper foil with a carrier copper foil (ultra-thin copper foil thickness 1.5 μm, surface roughness Rz 1.3 μm, carrier copper foil thickness 18 μm, MT-FL, manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides with the ultra-thin copper foil facing the resin composition powder. The plate was vacuum pressed at a pressure of 30 kg / cm and a temperature of 220°C for 120 minutes, after which the carrier copper foil was peeled and removed to obtain a cured plate with a side length of 100 mm and an insulating layer thickness of 1.0 mm. The resulting cured plate was evaluated for dielectric constant (Dk), dielectric loss tangent (Df), ESAP peel (copper foil peel strength), and minimum L / S (ability to form fine wiring). The evaluation results are shown in Table 1.

[0165] <Measurement and Evaluation Methods> (1) Dielectric Constant (Dk) and Dielectric Loss Tangent (Df) The ultrathin copper foils on both sides of the cured sheet obtained as described above were removed by etching, and then the sheet was downsized to 10 mm x 1.0 mm x 1.0 mm to obtain an evaluation sample. The obtained evaluation sample was dried at 120°C for 60 minutes, and then the dielectric constant (Dk) and dielectric loss tangent (Df) after drying at a frequency of 10 GHz were measured using a perturbation cavity resonator. The measurement temperature was 23°C. The perturbation cavity resonator used was a P5005A manufactured by Keysight Technologies. <<Dielectric Constant (Dk)>> A: 2.50 or less B: More than 2.50 <<Dielectric Loss Tangent (Df)>> A: 0.0025 or less B: More than 0.0025

[0166] <ESAP Peel> After the ultrathin copper foil of the cured sheet obtained as described above was removed by etching, electroless plating was performed to a thickness of 0.2 μm, and then electrolytic plating was performed to a copper thickness of 15 μm. The obtained plated substrate was diced to a size of 10 mm × 100 mm, and the copper foil peel strength (adhesion strength) was measured twice in accordance with the provisions of JIS C6481, 5.7 "Peel Strength", and the average value was calculated. The measurement temperature was 23 ° C.

[0167] <Minimum L / S> The obtained varnish was applied by bar coater coating onto the ultrathin copper foil surface of an ultrathin copper foil with a carrier copper foil (ultrathin copper foil thickness 1.5 μm, surface roughness Rz 1.3 μm, carrier copper foil thickness 18 μm, MT-FL, manufactured by Mitsui Mining & Smelting Co., Ltd.), and dried at 130° C. for 3 minutes to obtain a resin-coated copper foil with a resin thickness of 20 μm. Next, the obtained resin-coated copper foil was placed on both sides of a copper-clad laminate (HL-832NS, thickness 100 μm, manufactured by Mitsubishi Gas Chemical Company, Inc.), and a pressure of 30 kg / cm was applied. ２ The laminate was then vacuum pressed at 220°C for 120 minutes to obtain a circuit-forming laminate. The copper foil (carrier copper foil and ultrathin copper foil) on both sides of the resulting circuit-forming laminate was removed by etching, followed by electroless plating to a thickness of 0.2 μm. A photoresist was then laminated on the surface of the electroless plating layer, and the photoresist was exposed and developed to form resist patterns for forming various L / S wiring. Subsequently, electrolytic plating, resist pattern removal, and partial etching (flash etching) of the electroless plating layer were performed to form wiring with L / S ratios of 10 / 10, 5 / 5, 4 / 4, 3 / 3, and 2 / 2 (μm / μm, respectively). The resulting wiring was observed using a scanning electron microscope (SEM). A condition in which there was no peeling, collapse, distortion, or other abnormalities, and no remnants of the electroless plating layer were found between the wiring, was deemed to be "wiring formation successful." The smallest wiring pattern that could be formed is shown in Table 1. When a pattern with L / S=2 μm / 2 μm could be manufactured, the minimum L / S was shown as 2 / 2.

[0168] Example 2 The same procedure as in Example 1 was carried out except that the blending amount of the maleimide compound (ma) was changed to 35.0 parts by mass, the blending amount of the maleimide compound (mb) was changed to 35.0 parts by mass, and the blending amount of SNCN was changed to 10.0 parts by mass.

[0169] <Example 3> The same procedure was carried out as in Example 1, except that the amount of maleimide compound (ma) was changed to 30.0 parts by mass, the amount of maleimide compound (mb) was changed to 30.0 parts by mass, and 15.0 parts by mass of the polyphenylene ether compound (solid at 23°C) obtained in Synthesis Example 2 was added.

[0170] Example 4 The same procedure was carried out as in Example 1, except that the blending amount of the maleimide compound (ma) was changed to 27.5 parts by mass, the blending amount of the maleimide compound (mb) was changed to 27.5 parts by mass, and 20.0 parts by mass of a phosphorus-based flame retardant (PX-200, manufactured by Daihachi Chemical Industry Co., Ltd., 1,3-phenylenebis(2,6-dixylenyl phosphate), melting point 92°C) was blended.

[0171] Example 5 The same procedure was carried out as in Example 1, except that the blending amount of the maleimide compound (ma) was changed to 20.0 parts by mass, the blending amount of the maleimide compound (mb) was changed to 20.0 parts by mass, and 15.0 parts by mass of the polyphenylene ether compound obtained in Synthesis Example 2 and 20.0 parts by mass of the phosphorus-based flame retardant (PX-200) were blended.

[0172] Example 6 The same procedure was carried out as in Example 1, except that the blending amount of the maleimide compound (ma) was changed to 20.0 parts by mass, the blending amount of the maleimide compound (mb) was changed to 20.0 parts by mass, and 20.0 parts by mass of the polyphenylene ether compound obtained in Synthesis Example 2 and 15.0 parts by mass of the phosphorus-based flame retardant (PX-200) were blended.

[0173] <Example 7> The same procedure was carried out as in Example 1, except that the amount of maleimide compound (ma) was changed to 25.0 parts by mass, the amount of maleimide compound (mb) was changed to 25.0 parts by mass, and 25.0 parts by mass of the polyphenylene ether compound obtained in Synthesis Example 2 was added.

[0174] Comparative Example 1 The same procedure as in Example 1 was carried out except that the blending amount of the maleimide compound (ma) was changed to 42.5 parts by mass, the blending amount of the maleimide compound (mb) was changed to 42.5 parts by mass, SNCN was not blended, and the blending amount of the thermoplastic elastomer (TR2250) was changed to 15.0 parts by mass.

[0175]

[0176] REFERENCE SIGNS LIST 1 Multilayer body 2 Resin composition-containing layer 3 Inner layer circuit board 4 Metal foil 21 Insulating layer 22 Electroless plated layer 23 Resist pattern 24 Second plated layer 25 Wiring pattern

Claims

1. A multilayer body comprising a metal foil having a surface roughness Rz of 2 μm or less on at least one side in accordance with JIS B0601 1994, and a resin composition-containing layer provided on the surface of the metal foil having a surface roughness Rz of 2 μm or less, wherein the resin composition contains a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10°C or higher (however, the thermosetting compound may also be a thermosetting compound having an unshared electron pair).

2. The multilayer body according to claim 1, wherein the compound having an unshared electron pair and an aromatic ring, and having a melting point of 10°C or higher, and / or the thermosetting compound having an unshared electron pair, has a heteroatom.

3. The multilayer body according to claim 1, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher, and / or the thermosetting compound having an unshared electron pair, comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound.

4. The multilayer body according to claim 1, wherein the resin composition contains a maleimide compound.

5. The multilayer body according to claim 1, wherein the resin composition further comprises a filler.

6. The multilayer body according to claim 1, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair has a heteroatom, the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound, and the resin composition comprises a maleimide compound.

7. The multilayer body according to claim 6, wherein the resin composition further comprises a filler.

8. The multilayer body according to any one of claims 1 to 7, wherein the content of the cyanate ester compound contained in the resin composition is less than 1 part by mass per 100 parts by mass of resin solids.

9. The multilayer body according to any one of claims 1 to 7, which is used in the manufacture of printed wiring boards.

10. The multilayer body according to any one of claims 1 to 7, wherein the resin composition-containing layer is a resin sheet formed from the resin composition.

11. The multilayer body according to any one of claims 1 to 7, wherein the resin composition-containing layer is a prepreg formed from a substrate and the resin composition.

12. The multilayer body according to claim 11, wherein the substrate is glass cloth.

13. The multilayer body according to any one of claims 1 to 7, further comprising an inner layer circuit board, the resin composition-containing layer being provided on and in contact with the inner layer circuit board.

14. A multilayer body comprising a metal foil having a surface roughness Rz of 2 μm or less on at least one side in accordance with JIS B0601 1994, and an insulating layer which is a cured product of a resin composition-containing layer provided on the surface of the metal foil having a surface roughness Rz of 2 μm or less, wherein the resin composition contains a thermosetting compound and a compound having an unshared electron pair, an aromatic ring, and a melting point of 10°C or higher (however, the thermosetting compound may be a thermosetting compound having an unshared electron pair).

15. The multilayer body according to claim 14, wherein the compound having an unshared electron pair and an aromatic ring, and having a melting point of 10°C or higher, and / or the thermosetting compound having an unshared electron pair, contains a heteroatom.

16. The multilayer body according to claim 14, wherein the compound having an unshared electron pair, an aromatic ring, and a melting point of 10°C or higher, and / or the thermosetting compound having an unshared electron pair, comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound.

17. The multilayer body according to claim 14, wherein the resin composition comprises a maleimide compound.

18. The multilayer body of claim 14, wherein the resin composition further comprises a filler.

19. The multilayer body according to claim 14, wherein the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair has a heteroatom, the compound having an unshared electron pair and an aromatic ring and having a melting point of 10°C or higher and / or the thermosetting compound having an unshared electron pair comprises at least one compound selected from the group consisting of a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, a phosphate ester compound, and a cyanate ester compound, and the resin composition comprises a maleimide compound.

20. The multilayer body of claim 19, wherein the resin composition further comprises a filler.

21. The multilayer body according to any one of claims 14 to 20, wherein the content of the cyanate ester compound in the resin composition is less than 1 part by mass per 100 parts by mass of resin solids.

22. The multilayer body according to any one of claims 14 to 20, wherein the resin composition-containing layer is a resin sheet formed from the resin composition.

23. The multilayer body according to any one of claims 14 to 20, wherein the resin composition-containing layer is a prepreg formed from a substrate and the resin composition.

24. The multilayer body according to any one of claims 14 to 20, further comprising an inner layer circuit board, the insulating layer being provided on and in contact with the inner layer circuit board.

25. The multilayer body according to any one of claims 14 to 20, wherein the peel strength when the metal foil is removed from the multilayer body and the surface of the insulating layer is subjected to electroless plating treatment and electrolytic plating treatment is 0.35 kN / m or more.

26. A method for manufacturing a printed wiring board, comprising: removing the metal foil from the multilayer body according to any one of claims 14 to 20; performing electroless plating on the surface of the insulating layer from which the metal foil has been removed to form an electroless plated layer; forming a desired resist pattern on the surface of the electroless plated layer; performing plating on the surface on which the desired resist pattern has been formed to form a second plated layer; removing the resist pattern; and etching a portion of the electroless plated layer to expose the insulating layer and form a desired wiring pattern.

27. The method for manufacturing a printed wiring board according to claim 26, wherein the line width and space width of the wiring pattern are each 2 μm or less.

Images