Multilayer body, method for manufacturing multilayer body, printed wiring board, semiconductor device, and method for manufacturing printed wiring board

Abstract

Provided are a multilayer body capable of achieving reduction of transmission loss, a multilayer body, a method for manufacturing a multilayer body, a printed wiring board, a semiconductor device, and a method for manufacturing a printed wiring board. This multilayer body includes a first insulating resin layer, and a second insulating resin layer in contact with the first insulating resin layer. The dielectric loss tangent of the second insulating resin layer at a frequency of 10 GHz measured by a perturbation method cavity resonator is lower than the dielectric loss tangent of the first insulating resin layer.

Description

Multilayer body, multilayer body manufacturing method, printed wiring board, semiconductor device, and printed wiring board manufacturing method

[0001] The present invention relates to a multilayer body, a method for manufacturing a multilayer body, a printed wiring board, a semiconductor device, and a method for manufacturing a printed wiring board.

[0002] In recent years, various electronic devices, such as smartphones, have become lighter, thinner, shorter, and smaller, and data communication volumes have increased rapidly. Under these circumstances, printed wiring boards used in electronic devices have become increasingly compatible with high frequencies. Patent Document 1 and other publications have been cited as examples of studies of such printed wiring boards. Patent Document 1 discloses a prepreg, a metal-clad laminate, and a printed wiring board, each of which includes a first resin layer and a second resin layer provided on both sides of the first resin layer, wherein the first resin layer is a semi-cured product of a first resin composition that does not contain hexagonal boron nitride and is impregnated into glass cloth, and the second resin layer is a semi-cured product of a second resin composition that contains hexagonal boron nitride, the glass cloth having a warp and weft weave density of 54 threads or more per 25 mm, the hexagonal boron nitride having an average particle size of 10 to 30 μm, and the hexagonal boron nitride is contained in an amount of 20 to 40 parts by mass per 100 parts by mass of the remaining components of the second resin composition excluding the hexagonal boron nitride.

[0003] JP 2017-170748 A

[0004] Patent Document 1 states that the dielectric constant can be reduced by using the prepreg or the like described in Patent Document 1. However, no consideration has been given to transmission loss. Reduction of transmission loss is one of the most desirable performance characteristics in response to the trend toward lighter, thinner, shorter, and smaller electronic devices and the rapid increase in data communication volume. The present invention aims to solve this problem and provides a multilayer body capable of achieving reduced transmission loss, as well as a multilayer body, a method for manufacturing the multilayer body, a printed wiring board, a semiconductor device, and a method for manufacturing the printed wiring board.

[0005] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by using a multilayer body in which an insulating resin layer having a lower dielectric loss tangent than that of the insulating resin layer is provided on the surface of the insulating resin layer. Specifically, the above-mentioned problems have been solved by the following means. <1> A multilayer body having a first insulating resin layer and a second insulating resin layer in contact with the first insulating resin layer, wherein the dielectric loss tangent of the second insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator is lower than the dielectric loss tangent of the first insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator. <2> The multilayer body according to <1>, in which the first insulating resin layer has a thermal expansion coefficient of 30 ppm / °C or less as measured using a thermo-mechanical analysis (TMA) method. <3> The multilayer body according to <1> or <2>, in which the difference between the dielectric loss tangent of the second insulating resin layer and the dielectric loss tangent of the first insulating resin layer is 0.002 or more. <4> The multilayer body according to any one of <1> to <3>, wherein the first insulating resin layer has a coefficient of thermal expansion of 30 ppm / °C or less as measured according to a thermo-mechanical analysis (TMA) method, and wherein the difference between the dielectric loss tangent of the second insulating resin layer and the dielectric loss tangent of the first insulating resin layer is 0.002 or more. <5> The multilayer body according to any one of <1> to <4>, wherein the first insulating resin layer contains a fibrous base material. <6> The multilayer body according to any one of <1> to <5>, wherein the first insulating resin layer is a layer formed from a resin composition (1) containing a thermosetting compound and a fibrous base material. <7> The multilayer body according to any one of <1> to <6>, wherein the second insulating resin layer does not contain a fibrous base material. <8> The multilayer body according to <7>, wherein the second insulating resin layer is a layer formed from a resin composition (2), the resin composition (2) contains a thermosetting compound, and the content of a filler is 0 to 40 mass% of the mass of the resin solid content contained in the resin composition (2). <9> The multilayer body according to any one of <1> to <8>, wherein the second insulating resin layer is disposed so as to be in contact with both surfaces of the first insulating resin layer. <10> The multilayer body according to <9>, wherein a metal foil is further disposed so as to be in contact with the surface of the second insulating resin layer opposite to the first insulating resin layer.<11> The multilayer body according to any one of <1> to <10>, wherein a metal foil is further arranged so as to be in contact with the surface of the second insulating resin layer opposite to the first insulating resin layer. <12> The multilayer body according to any one of <1> to <11>, wherein the coefficient of thermal expansion of the first insulating resin layer measured in accordance with a TMA (Thermo-mechanical analysis) method is 30 ppm / °C or less, a difference between the dielectric loss tangent of the second insulating resin layer and the dielectric loss tangent of the first insulating resin layer is 0.002 or more, the first insulating resin layer is a layer formed from a resin composition (1) containing a thermosetting compound and a fiber base material, the second insulating resin layer does not contain a fiber base material, the second insulating resin layer is a layer formed from a resin composition (2), the resin composition (2) contains a thermosetting compound, and a content of a filler is 0 to 40 mass% of the mass of the resin solid content contained in the resin composition (2), and the second insulating resin layer is disposed so as to be in contact with both surfaces of the first insulating resin layer. <13> The multilayer body according to <12>, wherein a metal foil is further disposed so as to contact the surface of the second insulating resin layer opposite to the first insulating resin layer. <14> The multilayer body according to <13>, wherein a metal wiring is further provided on the surface of the second insulating resin layer. <15> The multilayer body according to <14>, wherein a third insulating resin layer is provided on the surface of the second insulating resin layer and covers the metal wiring. <16> The multilayer body according to any one of <1> to <15>, wherein the first insulating resin layer is a layer formed from a resin composition (1) and a fiber base material, and the resin composition (1) is in a cured state, the second insulating resin layer is a layer formed from a resin composition (2), and the resin composition (2) is in a cured state, the resin composition (1) contains a thermosetting compound, and the resin composition (2) contains a thermosetting compound, and the content of a filler is 0 to 40 mass% of the mass of the resin solid content contained in the resin composition (2). <17> A method for producing a multilayer body according to any one of <1> to <16>, comprising bonding a second insulating resin layer side of a second insulating resin layer having a metal foil on one surface to the first insulating resin layer.<18> A method for producing the multilayer body according to <17>, comprising obtaining the second insulating resin layer having a metal foil on one surface by removing a protective film from a metal foil-covered second insulating resin layer having a metal foil on one surface and a protective film on the other surface. <19> A method for producing the multilayer body according to <17> or <18>, comprising bonding the first insulating resin layer and the second insulating resin layer in a semi-cured state. <20> A printed wiring board comprising the multilayer body according to any one of <1> to <16>. <21> A semiconductor device comprising the printed wiring board according to <20>. <22> A method for producing a printed wiring board, comprising the method for producing the multilayer body according to any one of <17> to <19>.

[0006] According to the present invention, it is possible to provide a multilayer body capable of achieving a reduction in transmission loss, as well as a multilayer body, a method for manufacturing a multilayer body, a printed wiring board, a semiconductor device, and a method for manufacturing a printed wiring board.

[0007] Fig. 1 is a schematic diagram showing an example of a multilayer body (metal foil-clad laminate) of an embodiment. Fig. 2 is a schematic diagram showing another example of a multilayer body of an embodiment. Fig. 3 is a schematic diagram showing yet another example of a multilayer body of an embodiment. Fig. 4 is a schematic diagram showing a method for producing a multilayer body of an embodiment.

[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 both or either of allyl and methallyl, and "(meth)acrylic" refers to both or either of acrylic and methacrylic.

[0010] In this specification, the term "process" does not only refer to an independent process, but also includes processes that cannot be clearly distinguished from other processes as long as the process achieves its intended effect. If the measurement methods, etc. 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, etc. described in the standards shown in this specification are abolished as of January 1, 2023, they will be based on the standards in effect at the time of abolition. The scales of Figures 1 to 4 may not be consistent with reality.

[0011] A semi-cured state (semi-cured product) refers to a state between an uncured state and a cured state (fully cured state). When a semi-cured state is heated, it melts once and then becomes a cured state. Examples of uncured states include a resin composition containing a solvent and a varnish. Examples of semi-cured states include the resin solid content in a prepreg formed from a resin composition (such as a component from which the solvent in the resin composition has been removed), and the resin solid content in a metal foil-clad laminate containing the prepreg. Examples of cured states include the resin solid content in a metal foil-clad laminate where the resin solid content has been completely cured, and the resin solid content derived from the resin composition present in a printed wiring board. Furthermore, a layer formed from a resin composition may be in an uncured state, a semi-cured state, or a cured state. The resin composition is preferably in an uncured state, and the layer formed from the resin composition is preferably in a semi-cured and / or cured state.

[0012] In this specification, the resin solid content refers to components excluding fillers and solvents, and is intended to include thermosetting compounds, resin additives, etc. In this specification, the terms relative permittivity and dielectric constant are used interchangeably.

[0013] The multilayer body of this embodiment includes a first insulating resin layer and a second insulating resin layer in contact with the first insulating resin layer, and is characterized in that the dielectric loss tangent of the second insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator is lower than the dielectric loss tangent of the first insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator. This configuration effectively reduces transmission loss in the metal wiring provided on the surface of the second insulating resin layer. This is presumably because the second insulating resin layer has a lower dielectric loss tangent, enabling efficient signal transmission even at high frequencies.

[0014] In this embodiment, the difference in dielectric loss tangent between the first insulating resin layer and the second insulating resin layer in contact with the first insulating resin layer is preferably 0.002 or more, more preferably 0.003 or more, even more preferably 0.004 or more, and preferably 0.01 or less. By making the difference equal to or greater than the lower limit, the dielectric loss tangent of the second insulating resin layer becomes relatively low, and the low transmission loss effect of the multilayer body tends to be further improved. Furthermore, by making the difference equal to or less than the upper limit, the thermal expansion characteristics of the first insulating resin layer become relatively low, and the low thermal expansion effect of the multilayer body tends to be further improved. When there are two second insulating resin layers in contact with the first insulating resin layer, the difference in dielectric loss tangent is defined as the difference between the values ​​of the layers with the larger difference in dielectric loss tangent. It is preferable that both second insulating resin layers in contact with the first insulating resin layer satisfy the difference in dielectric loss tangent.

[0015] In this embodiment, the dielectric loss tangent of the first insulating resin layer is preferably 0.011 or less, more preferably 0.008 or less, and is usually greater than 0.004, and may be greater than 0.005 or even greater than 0.008. In this embodiment, even if the dielectric loss tangent of the first insulating resin layer is somewhat high, the transmission loss of the entire multilayer body can be reduced, and therefore the first insulating resin layer can have a composition that provides a lower thermal expansion coefficient.

[0016] In this embodiment, the dielectric loss tangent of the second insulating resin layer is preferably 0.011 or less, more preferably 0.008 or less, even more preferably 0.005 or less, and even more preferably 0.004 or less. The lower limit of the dielectric loss tangent of the second insulating resin layer is the better, but even if it is 0.0001 or more, the required performance is sufficiently satisfied. The dielectric loss tangent is measured according to the method described in the examples below.

[0017] The thickness of the multilayer body of this embodiment is not particularly limited, but the total thickness of the first insulating resin layer, the second insulating resin layer, and the metal foil provided as needed is preferably 3000 μm or less, more preferably 2500 μm or less, and even more preferably 2000 μm or less, and is preferably 100 μm or more, more preferably 150 μm or more, and even more preferably 200 μm or more. By setting the thickness to be equal to or less than the above upper and lower limits, the dielectric loss tangent of the multilayer body tends to be lower.

[0018] In the multilayer body of this embodiment, it is preferable that the thickness of the second insulating resin layer is thinner than the thickness of the first insulating resin layer, because the skin effect is achieved in the second insulating resin layer, making it easier for electrical signals to pass through.

[0019] In the multilayer body of this embodiment, the ratio of the thickness of the first insulating resin layer to the thickness of the second insulating resin layer in contact with the first insulating resin layer is preferably 0.9 or less, more preferably 0.8 or less, even more preferably 0.7 or less, and even more preferably 0.6 or less, relative to the thickness of the first insulating resin layer. It is also preferably 0.0001 or more, more preferably 0.0005 or more, and even more preferably 0.00 or more. By setting the ratio below the upper limit, the dielectric loss tangent of the multilayer body tends to be lower. Furthermore, by setting the ratio above the lower limit, the dielectric loss tangent of the multilayer body tends to be lower and transmission loss tends to be more effectively suppressed. When two second insulating resin layers are in contact with the first insulating resin layer, the thickness of the thinner second insulating resin layer is defined as the thickness described above.

[0020] In the multilayer body of this embodiment, the thickness of the first insulating resin layer is preferably 5000 μm or less, more preferably 4000 μm or less, and even more preferably 3000 μm or less, and is preferably 100 μm or more, more preferably 150 μm or more, and even more preferably 200 μm or more.

[0021] In the multilayer body of this embodiment, the thickness of the second insulating resin layer is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and even more preferably 100 μm or less, and is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and even more preferably 10 μm or more. By setting the thickness to the upper limit or less, the thermal expansion coefficient of the multilayer body tends to be lower. Furthermore, by setting the thickness to the lower limit or more, the transmission loss of the multilayer body tends to be lower.

[0022] Next, the layer structure of the multilayer body of this embodiment is shown with reference to the drawings. FIG. 1 shows an example of a multilayer body (metal foil-clad laminate) of this embodiment, where 1 indicates the multilayer body, 2 indicates a first insulating resin layer, 3 indicates a second insulating resin layer in contact with the first insulating resin layer, and 4 indicates a metal foil. In this embodiment, the metal foil 4 is not essential, and the multilayer body may be a two-layer body consisting of a first insulating resin layer 2 and a second insulating resin layer 3, or a three-layer body consisting of a second insulating resin layer 3 / first insulating resin layer 2 / second insulating resin layer 3 laminated in this order. Other layers may also be included within the scope of the present invention. In FIG. 1, the second insulating resin layers 3 / 3 are arranged so as to be in contact with both sides of the first insulating resin layer 2. In FIG. 1, metal foils 4 / 4 are arranged so as to be in contact with the surfaces of the second insulating resin layers 3 / 3 opposite the first insulating resin layer 2. The configuration of FIG. 1 is suitable as a transport stage for materials before processing for printed wiring boards (particularly for circuit boards). The multilayer body of this embodiment does not necessarily have to have a second insulating resin layer 3 and a metal foil 4 provided on both sides of a single first insulating resin layer, as shown in FIG. 1 . For example, a configuration in which a second insulating resin layer is provided on one side of a single first insulating resin layer may be used, or a configuration in which a second insulating resin layer is provided on one side of a single first insulating resin layer, and a metal foil is further disposed so as to contact the surface of the second insulating resin layer opposite the first insulating resin layer. Furthermore, the two second insulating resin layers 3 in FIG. 1 may be the same layer, or may be second insulating resin layers with different thicknesses and / or compositions. The same applies to the metal foils.

[0023] Figure 2 shows another example of the multilayer body of this embodiment, which has a second insulating resin layer 3 on the surface of a first insulating resin layer 2, but no metal foil. Also, in Figure 2, metal wiring 5 is provided on the surface of the second insulating resin layer 3. The metal wiring is preferably copper wiring, and the metal wiring is formed by a known method, such as a subtractive method in which a circuit is formed by etching a metal foil, or a (semi-)additive method in which a conductor layer is formed on an insulating layer by plating. Such a multilayer body is preferably used as a circuit board.

[0024] FIG. 3 shows yet another example of the multilayer body of the present invention, which has metal wiring 5 provided on the surface of the second insulating resin layer 3 and a third insulating resin layer 6 covering the metal wiring 5. That is, as shown in FIG. 2 , the multilayer body can be formed by providing metal wiring 5 on the surface of the second insulating resin layer 3 and then covering it with the third insulating resin layer 6. The third insulating resin layer 6 is typically preferably made of the same material as the second insulating resin layer 3, as described below. Yet another example of the multilayer body of the present invention includes a first insulating resin layer, metal wiring provided on the surface of the first insulating resin layer, and a second insulating resin layer provided on the surface of the first insulating resin layer and covering the metal wiring, wherein the dielectric loss tangent of the second insulating resin layer at a frequency of 10 GHz measured with a perturbation cavity resonator is lower than the dielectric loss tangent of the first insulating resin layer at a frequency of 10 GHz measured with a perturbation cavity resonator. The details of the first insulating resin layer and the second insulating resin layer are the same as those described above, and the preferred ranges are also the same.

[0025] An example of an embodiment of the multilayer body of this embodiment is when the multilayer body is used in an application requiring a low thermal expansion coefficient. One of the performance requirements for printed wiring boards is a low thermal expansion coefficient. Furthermore, suppression of warping during heating is sometimes required. When the multilayer body of this embodiment is used in an application requiring these performance requirements, the thermal expansion coefficient of the first insulating resin layer, measured in accordance with the TMA (thermo-mechanical analysis) method, is preferably 30 ppm / °C or less. Because the thermal expansion coefficient of the first insulating resin layer is low in this way, even if the thermal expansion coefficient of the second insulating resin layer is high, an increase in the thermal expansion coefficient of the multilayer body can be suppressed, and warping of the multilayer body can also be suppressed. As a result, it is possible to impart other functions (further low dielectric properties (Dk and / or Df)) to the second insulating resin layer in addition to low thermal expansion and low warping. The thermal expansion coefficient referred to here is measured in accordance with the TMA method (Thermo-Mechanical Analysis) specified in JIS C 6481 5.19, and refers to the thermal expansion coefficient in the in-plane direction (CTE(XY)) from 50°C to 280°C when the temperature is increased from 30°C to 320°C at a rate of 10°C per minute, and more specifically, is measured by the method described in the examples.

[0026] Therefore, the thermal expansion coefficient of the first insulating resin layer is preferably 30 ppm / ° C. or less, more preferably 25 ppm / ° C. or less, even more preferably 20 ppm / ° C. or less, even more preferably 15 ppm / ° C. or less, and still more preferably 10 ppm / ° C. or less. The lower limit of the thermal expansion coefficient of the first insulating resin layer is preferably 0 ppm / ° C., but even if it is 1 ppm / ° C. or more, the required performance is sufficiently satisfied.

[0027] The low thermal expansion coefficient of the first insulating resin layer can be achieved, for example, by increasing the proportion of filler in the first insulating resin layer (e.g., greater than the proportion of filler in the second insulating resin layer). That is, by reducing the proportion of resin components that are prone to thermal expansion in the first insulating resin layer, the thermal expansion of the first insulating resin layer can be effectively suppressed. The first insulating resin layer preferably contains a fibrous base material. Details of the composition of the first insulating resin layer will be described later.

[0028] On the other hand, insulating resin layers containing fillers, particularly fibrous substrates, tend to have uneven surfaces, resulting in variations in electronic signals. Therefore, when the first insulating resin layer contains a filler, particularly a fibrous substrate, it is preferable that the second insulating resin layer does not contain a filler (particularly a fibrous substrate). This configuration results in a smooth surface, thereby more effectively reducing the transmission loss of the resulting multilayer body. The composition of the second insulating resin layer will be described in detail below. In this case, the second insulating resin layer tends to contain a smaller amount of filler than the first insulating resin layer, so it is particularly preferable that it does not contain a fibrous substrate. Therefore, the thermal expansion coefficient of the second insulating resin layer usually tends to be higher than that of the first insulating resin layer. The thermal expansion coefficient of the second insulating resin layer may be, for example, greater than 10 ppm / °C, or even greater than 15 ppm / °C, and is preferably 30 ppm / °C or less.

[0029] <First Insulating Resin Layer> The first insulating resin layer of this embodiment is not particularly limited as long as it has a dielectric loss tangent equal to or greater than that of the second insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator (preferably greater than that of the second insulating resin layer). The first insulating resin layer is typically a layer formed from a resin composition (1) containing a thermosetting compound and a fiber substrate, or a layer formed from a resin composition (1) containing a thermosetting compound, preferably a layer formed from a resin composition (1) containing a thermosetting compound and a fiber substrate. In the layer formed from the resin composition (1), the resin solid content contained in the resin composition (1) may be in an uncured state, a semi-cured state, or a cured state. Preferably, the resin solid content contained in the resin composition (1) is in a semi-cured or cured state.

[0030] The thermosetting compound contained in the resin composition (1) is preferably a thermosetting compound containing at least one group selected from the group consisting of (meth)allyl compounds, maleimide compounds, epoxy compounds, cyanate ester compounds, phenolic compounds, oxetane compounds, benzoxazine compounds, compounds having polymerizable unsaturated groups other than the above compounds, silicone-modified thermosetting compounds, and BT resins. BT resins are polymerized cyanate ester compounds and maleimide compounds. The thermosetting compounds may also include, for example, epoxy compounds containing (meth)allyl groups. For such compounds, compounds explicitly listed in any of the categories described below, such as "(meth)allyl compounds," are classified as such (e.g., (meth)allyl compounds). Compounds not explicitly listed are classified as compounds described in the preceding paragraphs of this specification.

[0031] The total amount of the thermosetting compound in the resin composition (1) 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, even more preferably 50 parts by mass or more, even more preferably 70 parts by mass or more, and is preferably 99 parts by mass or less, more preferably 95 parts by mass or less, even more preferably 90 parts by mass or less, relative to 100 parts by mass of the resin solid content. The resin composition (1) may contain only one type of 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.

[0032] A first example of a blend of thermosetting compounds in resin composition (1) is a blend containing at least one selected from (meth)allyl compounds, maleimide compounds, epoxy compounds, cyanate ester compounds, phenolic compounds, benzoxazine compounds, and compounds having a polymerizable unsaturated group other than the above compounds, and at least one silicone-modified thermosetting compound. More preferably, the first example of a blend of thermosetting compounds in resin composition (1) contains at least one selected from (meth)allyl compounds, maleimide compounds, epoxy compounds, and cyanate ester compounds, and at least one silicone-modified thermosetting compound.

[0033] In a first example of a blend of thermosetting compounds in the resin composition (1), the content of the silicone-modified thermosetting compound is preferably 1 part by mass or more, preferably 50 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the resin solids. In a first example of a blend of thermosetting compounds in the resin composition (1), the content of the thermosetting compounds other than the silicone-modified thermosetting compound is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 70 parts by mass or more, per 100 parts by mass of the resin solids. Preferably, the thermosetting compound other than the silicone-modified thermosetting compound is at least one selected from (meth)allyl compounds, maleimide compounds, epoxy compounds, cyanate ester compounds, phenolic compounds, benzoxazine compounds, and compounds having a polymerizable unsaturated group other than the above compounds.

[0034] A second example of a blend of thermosetting compounds in resin composition (1) is a blend containing one or more compounds selected from the group consisting of (meth)allyl compounds, maleimide compounds, epoxy compounds, cyanate ester compounds, phenolic compounds, benzoxazine compounds, compounds having a polymerizable unsaturated group other than the above compounds, and BT resin. In the second example, the blend preferably contains one or more compounds selected from the group consisting of maleimide compounds, epoxy compounds, cyanate ester compounds, phenolic compounds, and BT resin in a total amount of 90 parts by mass or more per 100 parts by mass of the resin solids. In the second example of a blend of thermosetting compounds in resin composition (1), the blend preferably contains 3 to 50 parts by mass of the maleimide compound per 100 parts by mass of the total thermosetting compounds. In the second example of a blend of thermosetting compounds in resin composition (1), the blend preferably contains 10 to 80 parts by mass of the epoxy compound per 100 parts by mass of the total thermosetting compounds. In a second example of a blend of thermosetting compounds in the resin composition (1), the resin composition preferably contains 10 to 60 parts by mass of a cyanate ester compound relative to 100 parts by mass of the total thermosetting compounds. In a second example of a blend of thermosetting compounds in the resin composition (1), the resin composition preferably contains 10 to 60 parts by mass of a phenol compound relative to 100 parts by mass of the total thermosetting compounds. In a second example of a blend of thermosetting compounds in the resin composition (1), the resin composition preferably contains 20 to 80 parts by mass of a BT resin relative to 100 parts by mass of the total thermosetting compounds. In a second example of a blend of thermosetting compounds in the resin composition (1), the resin composition preferably does not substantially contain a silicone-modified thermosetting compound. "Substantially not containing" means that the content of the silicone-modified thermosetting compound in the resin composition (1) is less than 3 parts by mass, preferably less than 1 part by mass, and may be less than 0.1 parts by mass, relative to 100 parts by mass of the resin solids. Details of these thermosetting compounds are described below.

[0035] <<(Meth)allyl Compound>> The (meth)allyl compound 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 still more preferably 2) (meth)allyl groups per molecule, and a wide variety of (meth)allyl compounds commonly used in the field of printed wiring boards can be used. In this embodiment, the (meth)allyl compound is preferably an allyl compound.

[0036] An example of the (meth)allyl compound is a (meth)allyl phenol compound. The (meth)allyl phenol compound preferably has one or more structures in which one or more (meth)allyl groups are directly bonded to a phenolic aromatic ring. The (meth)allyl phenol compound preferably has one or two structures in which one or more (meth)allyl groups are directly bonded to a phenolic aromatic ring, and more preferably has two structures.

[0037] The (meth)allylphenol compound may be, for example, a compound represented by formula (1A) or formula (1B). (In formula (1A), each Rxa independently represents a (meth)allyl group; each Rxb independently represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom; each Rxc independently represents an aromatic ring having 4 to 12 carbon atoms; Rxc may form a condensed structure with a benzene ring; Rxc may or may not be present; A represents an alkylene group having 1 to 6 carbon atoms, an aralkylene group having 7 to 16 carbon atoms, an arylene group having 6 to 10 carbon atoms, a fluorenylidene group, a sulfonyl group, an oxygen atom, a sulfur atom, or a direct bond (single bond); when Rxc is not present, one benzene ring may have two or more Rxa and / or Rxb groups.) (In formula (1B), each Rxd independently represents a (meth)allyl group, each Rxe independently represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom, and Rxf represents an aromatic ring having 4 to 12 carbon atoms, which may form a condensed structure with a benzene ring, and which may or may not be present. When Rxf is not present, one benzene ring may have two or more Rxd and / or Rxe groups.)

[0038] In the formulas (1A) and (1B), when the groups represented by Rxc and Rxf form a condensed structure with a benzene ring, for example, a compound containing a naphthol ring as the phenolic aromatic ring can be mentioned. In addition, in the formulas (1A) and (1B), when the groups represented by Rxc and Rxf are not present, for example, a compound containing a phenol ring as the phenolic aromatic ring can be mentioned.

[0039] In formula (1A) and formula (1B), the alkyl group having 1 to 10 carbon atoms represented by Rxb and Rxe is not particularly limited, and examples thereof include linear alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and branched alkyl groups such as an isopropyl group, an isobutyl group, and a tert-butyl group.

[0040] In formula (1A), the alkylene group having 1 to 6 carbon atoms represented by A is not particularly limited, but examples thereof include a methylene group, an ethylene group, a trimethylene group, and a propylene group. The aralkylene group having 7 to 16 carbon atoms represented by A is not particularly limited, but examples thereof include the formula: -CH ２ -Ar-CH ２ -, -CH ２ -CH ２ -Ar-CH ２ -CH ２ -, or the formula: -CH ２ -Ar-CH ２ -CH ２ - (wherein Ar represents a phenylene group, a naphthylene group, or a biphenylene group). The arylene group having 6 to 10 carbon atoms represented by A is not particularly limited, and examples thereof include a phenylene ring.

[0041] In the compound represented by formula (1B), Rxf is preferably a benzene ring (a compound containing a dihydroxynaphthalene skeleton).

[0042] From the viewpoint of further improving compatibility, the (meth)allyl phenol compound is preferably (meth)allyl bisphenol in which one (meth)allyl group is bonded to each of two phenolic aromatic rings of a bisphenol. From the same viewpoint, the (meth)allyl bisphenol is preferably diallyl bisphenol in which one (meth)allyl group is bonded to each of two phenolic aromatic rings of a bisphenol, and / or dipropenyl bisphenol in which one propenyl group is bonded to each of two phenolic aromatic rings of a bisphenol.

[0043] The diallyl bisphenol is not particularly limited, but examples thereof include o,o'-diallyl bisphenol A ("DABPA" manufactured by Daiwa Chemical Industry Co., Ltd.), o,o'-diallyl bisphenol F, o,o'-diallyl bisphenol S, and o,o'-diallyl bisphenol fluorene. The dipropenyl bisphenol is not particularly limited, but examples thereof include o,o'-dipropenyl bisphenol A ("PBA01" manufactured by Gunei Chemical Industry Co., Ltd.), o,o'-diallyl bisphenol F, o,o'-dipropenyl bisphenol S, and o,o'-dipropenyl bisphenol fluorene.

[0044] The average number of phenol groups per molecule of the (meth)allylphenol compound is preferably 1 or more and less than 3, and more preferably 1.5 or more and 2.5 or less. The average number of phenol groups is calculated by the following formula.

[0045] In the formula, Ai represents the number of phenol groups in an alkenylphenol having i phenol groups in the molecule, Xi represents the proportion of alkenylphenols having i phenol groups in the molecule to all alkenylphenols, and X1 + X2 + ... Xn = 1.

[0046] Another example of the (meth)allyl compound is a (meth)allyl-substituted nadimide compound. The (meth)allyl-substituted nadimide compound is not particularly limited as long as it is a compound having one or more (meth)allyl-substituted nadimide groups in one molecule, and examples thereof include compounds represented by formula (2d):

[0047]

[0048] In formula (2d), R １ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms (for example, a methyl group or an ethyl group), and R ２ represents an alkylene group having 1 to 6 carbon atoms, a phenylene group, a biphenylene group, a naphthylene group, or a group represented by the following formula (7) or (8).

[0049]

[0050] In formula (7), R ３ represents a methylene group, an isopropylidene group, —C(═O)—, —O—, —S—, or —SO ２ Indicates -.

[0051] In formula (8), R ４ are each independently an alkylene group having 1 to 4 carbon atoms or a cycloalkylene group having 5 to 8 carbon atoms.

[0052] The (meth)allyl-substituted nadimide compound represented by formula (2d) may be a commercially available product, or a product produced according to a known method. Examples of commercially available products include "BANI-M" and "BANI-X" manufactured by Maruzen Petrochemical Co., Ltd.

[0053] In addition to the above, for details of the (meth)allyl compound, the descriptions in paragraphs 0016 to 0030 of WO 2020 / 022084 and paragraphs 0141 to 0160 of WO 2023 / 013709 can be referred to, the contents of which are incorporated herein by reference.

[0054] When the resin composition (1) contains a (meth)allyl compound, the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the resin solid content, and is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less. The resin composition (1) may contain only one type of (meth)allyl 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.

[0055] <<Maleimide Compound>> The maleimide compound 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 still more preferably 2) maleimide groups in one molecule, and a wide variety of maleimide compounds commonly used in the field of printed wiring boards can be used.

[0056] Examples of the maleimide compound include maleimide compounds that may be incorporated into the resin composition (2) described below, and preferably include one or more selected from the group consisting of compounds represented by formula (M0), compounds represented by formula (M1), compounds represented by formula (M2), compounds represented by formula (M3), compounds represented by formula (M4), compounds represented by formula (M5), maleimide compounds (M6), maleimide compounds (M7), and maleimide compounds (M8), which are described in the resin composition (2) described below. More preferably, the maleimide compound includes one or more selected from the group consisting of compounds represented by formula (M0), compounds represented by formula (M2), compounds represented by formula (M3), compounds represented by formula (M4), and compounds represented by formula (M5). More preferably, the maleimide compound includes a compound represented by formula (M2) and / or a compound represented by formula (M3).

[0057] In addition to the above, for details of the maleimide compound, see paragraphs 0092 to 0095 of WO 2020 / 022084, paragraphs 0103 to 0110 of WO 2023 / 013709, and paragraphs 0044 to 0045 of Japanese Patent No. 6414799. The contents of these paragraphs are incorporated herein by reference.

[0058] When the resin composition (1) contains a maleimide compound, the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the resin solid content, and is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less. The resin composition (1) may contain only one type of maleimide compound, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0059] <<Epoxy Compound>> The epoxy compound 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 still more preferably 2) epoxy groups in one molecule, and a wide variety of epoxy compounds commonly used in the field of printed wiring boards can be used.

[0060] It should be noted that epoxy-modified silicones, which will be described separately below, are not included in the epoxy compounds in this section.

[0061] Examples of epoxy compounds include bisphenol-type epoxy resins (e.g., bisphenol A-type epoxy resins, bisphenol E-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins), diallyl bisphenol-type epoxy resins (e.g., diallyl bisphenol A-type epoxy resins, diallyl bisphenol E-type epoxy resins, diallyl bisphenol F-type epoxy resins, and diallyl bisphenol S-type epoxy resins), phenol novolac-type epoxy resins (e.g., phenol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, and cresol novolac-type epoxy resins), aralkyl-type epoxy resins, biphenyl-type epoxy resins containing a biphenyl skeleton, naphthalene-type epoxy resins containing a naphthalene skeleton, anthracene-type epoxy resins containing a dihydroanthracene skeleton, glycidyl esters, polyol-type epoxy resins, isocyanurate ring-containing epoxy resins, dicyclopentadiene-type epoxy resins, epoxy resins composed of bisphenol A-type structural units and hydrocarbon-based structural units, and halogen compounds thereof. These epoxy compounds may be used alone or in combination of two or more.

[0062] Among these, from the viewpoint of further improving chemical resistance, copper foil adhesion, and insulation reliability, the epoxy compound is preferably at least one selected from the group consisting of aralkyl epoxy resins, naphthalene epoxy resins, dicyclopentadiene epoxy resins, and epoxy resins comprising bisphenol A structural units and hydrocarbon-based structural units, and more preferably contains a naphthalene epoxy resin.

[0063] <<<Aralkyl Epoxy Resin>>> The aralkyl epoxy resin is not particularly limited, but examples thereof include compounds represented by formula (3a). (In formula (3a), Ar ３ each independently represents a benzene ring or a naphthalene ring; Ar ４ represents a benzene ring, a naphthalene ring, or a biphenyl ring; R ３ａeach independently represents a hydrogen atom or a methyl group, k represents an integer of 1 to 50, and each ring may have a substituent other than a glycidyloxy group (for example, an alkyl group having 1 to 5 carbon atoms or a phenyl group).

[0064] The compound represented by formula (3a) is Ar ３ is a naphthalene ring, and Ar ４ is a benzene ring (also referred to as "naphthalene aralkyl type epoxy resins"); ３ is a benzene ring, and Ar ４ is a biphenyl ring (also referred to as a "biphenyl aralkyl type epoxy resin"), and a biphenyl aralkyl type epoxy resin is more preferred.

[0065] The biphenylaralkyl epoxy resin is preferably a compound represented by formula (3b). (In formula (3b), ka represents an integer of 1 or more, preferably 1 to 20, and more preferably 1 to 6.)

[0066] The aralkyl epoxy resin may be a compound represented by formula (3c). (In formula (3c), ky represents an integer of 1 to 10.)

[0067] The aralkyl epoxy resin may be a commercially available product, or a preparation prepared by a known method. Commercially available naphthalene aralkyl epoxy resins include "Epotohto (registered trademark) ESN-155," "Epotohto (registered trademark) ESN-355," "Epotohto (registered trademark) ESN-375," "Epotohto (registered trademark) ESN-475V," "Epotohto (registered trademark) ESN-485," and "Epotohto (registered trademark) ESN-175" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "NC-7000," "NC-7300," and "NC-7300L" manufactured by Nippon Kayaku Co., Ltd., and "HP-5000" and "HP-9900" manufactured by DIC Corporation. Commercially available biphenylaralkyl epoxy resins include, for example, "NC-3000," "NC-3000L," and "NC-3000FH" manufactured by Nippon Kayaku Co., Ltd.

[0068] <<<Naphthalene-Type Epoxy Resin>>> The naphthalene-type epoxy resin is not particularly limited, but examples thereof include naphthalene-skeleton-containing polyfunctional epoxy resins having a naphthalene skeleton represented by the following formula (3-1), and epoxy resins having a naphthalene skeleton, excluding the above-mentioned naphthalene aralkyl-type epoxy resins. Specific examples of naphthalene-type epoxy resins include naphthylene ether-type epoxy resins, and from the viewpoint of further improving chemical resistance, copper foil adhesion, and insulation reliability, naphthylene ether-type epoxy resins are preferred. (In formula (3-1), Ar ３１ each independently represents a benzene ring or a naphthalene ring; Ar ４１ represents a benzene ring, a naphthalene ring, or a biphenyl ring; R ３１ａ each independently represents a hydrogen atom or a methyl group, p represents an integer of 0 to 2, preferably 0 or 1, kz represents an integer of 1 to 50, each ring may have a substituent other than a glycidyloxy group (for example, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a phenyl group), and Ar ３１ and Ar ４１ At least one of the groups represents a naphthalene ring.) Examples of the compound represented by formula (3-1) include compounds represented by formula (3-2). (In formula (3-1), R represents a methyl group, and kz has the same meaning as kz in formula (3-1) above.)

[0069] The naphthalene skeleton-containing polyfunctional epoxy resin may be a commercially available product, or a product prepared by a known method. Examples of commercially available naphthalene skeleton-containing polyfunctional epoxy resins include "HP-9540" and "HP-9500" manufactured by DIC Corporation.

[0070] From the viewpoint of further improving chemical resistance, copper foil adhesion, and insulation reliability, the naphthylene ether type epoxy resin is preferably a compound represented by formula (3-3) or a compound represented by formula (3-4). (In the formula, R １３each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms (e.g., a methyl group or an ethyl group), or an alkenyl group having 2 to 3 carbon atoms (e.g., a vinyl group, an allyl group, or a propenyl group). (In formula (3-3), R １４ each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms (e.g., a methyl group or an ethyl group), or an alkenyl group having 2 to 3 carbon atoms (e.g., a vinyl group, an allyl group, or a propenyl group).

[0071] The naphthylene ether type epoxy resin may be a commercially available product, or a product prepared by a known method. Commercially available naphthylene ether type epoxy resins include, for example, DIC Corporation products "HP-6000", "EXA-7300", "EXA-7310", "EXA-7311", "EXA-7311L", "EXA7311-G3", "EXA7311-G4", "EXA-7311G4S", and "EXA-7311G5".

[0072] <<<Dicyclopentadiene-Type Epoxy Resin>>> The dicyclopentadiene-type epoxy resin is not particularly limited, but examples thereof include compounds represented by formula (3-5). (In the formula, R ３ｃ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and k2 represents an integer of 0 to 10.

[0073] The dicyclopentadiene type epoxy resin may be a commercially available product or a product prepared by a known method. Commercially available dicyclopentadiene type epoxy resins include "EPICRON HP-7200L," "EPICRON HP-7200," "EPICRON HP-7200H," and "EPICRON HP-7000HH" manufactured by Dainippon Ink and Chemicals, Inc.

[0074] <<<Epoxy Resin Composed of Bisphenol A Structural Units and Hydrocarbon-Based Structural Units>>> An epoxy resin composed of bisphenol A structural units and hydrocarbon-based structural units (also referred to as a "specific epoxy resin") has one or more bisphenol A structural units and one or more hydrocarbon-based structural units in the molecule. An example of the specific epoxy resin is a compound represented by the following formula (3e): (In the formula, R １ｘ and R ２ｘ each independently represents a hydrogen atom or a methyl group, R ３ｘ ~R ６ｘ each independently represents a hydrogen atom, a methyl group, a chlorine atom, or a bromine atom; X represents an ethyleneoxyethyl group, a di(ethyleneoxy)ethyl group, a tri(ethyleneoxy)ethyl group, a propyleneoxypropyl group, a di(propyleneoxy)propyl group, a tri(propyleneoxy)propyl group, or an alkylene group having 2 to 15 carbon atoms; and k3 represents a natural number.

[0075] k3 represents a natural number, preferably 1 to 100, and more preferably 1 to 10.

[0076] The specific epoxy resin may be a commercially available product or a preparation prepared by a known method. Examples of commercially available specific epoxy resins include "EPICLON EXA-4850-150" and "EPICLON EXA-4816" manufactured by DIC Corporation.

[0077] In addition to the above, for details of the epoxy compound, see paragraphs 0117 to 0133 of WO 2020 / 022084, paragraphs 0189 to 0214 of WO 2023 / 013709, and paragraphs 0047 to 0053 of Japanese Patent No. 6414799. The contents of these paragraphs are incorporated herein by reference.

[0078] When the resin composition (1) contains an epoxy compound, the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the resin solid content, and is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less. The resin composition (1) may contain only one type of epoxy 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.

[0079] <<Cyanate Ester Compounds>> The cyanate ester compounds are not particularly limited as long as they are compounds having two or more cyanato groups (cyanate ester groups) in one molecule. Examples of the cyanate ester compounds include naphthol aralkyl cyanate ester compounds such as compounds represented by formula (5), novolak cyanate ester compounds such as compounds represented by formula (6) excluding the compounds represented by formula (5), biphenyl aralkyl cyanate esters, diallyl bisphenyl cyanate ester compounds, bis(3,3-dimethyl-4-cyanatophenyl)methane, bis(4-cyanatophenyl)methane, 1,3-dicyanato Examples of the cyanate ester compounds include benzene, 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-dicyanatonaphthalene, 1,4-dicyanatonaphthalene, 1,6-dicyanatonaphthalene, 1,8-dicyanatonaphthalene, 2,6-dicyanatonaphthalene, 2,7-dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4'-dicyanatobiphenyl, bis(4-cyanatophenyl)ether, bis(4-cyanatophenyl)thioether, bis(4-cyanatophenyl)sulfone, and 2,2-bis(4-cyanatophenyl)propane. These cyanate ester compounds may be used alone or in combination of two or more. Among these, from the viewpoint of further improving the low thermal expansion property and chemical resistance of the first insulating resin layer, the cyanate ester compound preferably includes a naphthol aralkyl-type cyanate ester compound and / or a novolac-type cyanate ester compound, and more preferably includes a compound represented by formula (5).

[0080] (In formula (5), R ６ each independently represents a hydrogen atom or a methyl group, n ２ represents an integer of 1 or more.) n ２ is preferably an integer of 1 to 20, more preferably an integer of 1 to 10, and even more preferably an integer of 1 to 6.

[0081] (In formula (6), R ｙａ each independently represents a (meth)allyl group having 2 to 8 carbon atoms or a hydrogen atom, and R ｙｂ each independently represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom, and R ｙｃ each independently represents an aromatic ring having 4 to 12 carbon atoms; R ｙｃ may form a condensed structure with a benzene ring, and R ｙｃ may or may not be present, and A １ａ each independently represents an alkylene group having 1 to 6 carbon atoms, an aralkylene group having 7 to 16 carbon atoms, an arylene group having 6 to 10 carbon atoms, a fluorenylidene group, a sulfonyl group, an oxygen atom, a sulfur atom, or a single bond (direct bond); R ｙｃ When R is not present, one benzene ring ｙａ and / or R ｙｂ n represents an integer of 1 to 20.

[0082] In formula (6), R ｙａ Examples of the (meth)allyl group having 2 to 8 carbon atoms represented by the formula (I) include a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group.

[0083] In formula (6), R ｙｂ Examples of the alkyl group having 1 to 10 carbon atoms represented by the formula (I) include linear alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group; and branched alkyl groups such as an isopropyl group, an isobutyl group, and a tert-butyl group.

[0084] In formula (6), A １ａExamples of the alkylene group having 1 to 6 carbon atoms represented by the formula (6) include a methylene group, an ethylene group, a trimethylene group, and a propylene group. １ａ Examples of the aralkylene group having 7 to 16 carbon atoms represented by the formula: ２ -Ar-CH ２ -, -CH ２ -CH ２ -Ar-CH ２ -CH ２ -, or the formula: -CH ２ -Ar-CH ２ -CH ２ - (wherein Ar represents a phenylene group, a naphthylene group, or a biphenylene group). １ａ Examples of the arylene group having 6 to 10 carbon atoms represented by the following formula include a phenylene ring.

[0085] In formula (6), n represents an integer of 1 to 20, preferably an integer of 1 to 15, and more preferably an integer of 1 to 10.

[0086] The compound represented by formula (6) is preferably a phenol novolac cyanate ester compound, and more preferably a compound represented by formula (c1), because it further improves the low thermal expansion and chemical resistance of the first insulating resin layer and has a higher glass transition temperature.

[0087]

[0088] In formula (c1), each Rx independently represents a hydrogen atom or a methyl group, each R independently represents an alkenyl group having 2 to 8 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or a hydrogen atom, and n represents an integer of 1 to 10.

[0089] These cyanate ester compounds may be produced according to known methods, such as those described in JP-A-2017-195334 (particularly paragraphs 0052 to 0057).

[0090] 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.

[0091] 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.

[0092] When the resin composition (1) 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 (1). When the cyanate ester compound content is 0.1 parts by mass or more, the first insulating resin layer tends to have excellent adhesion to the metal foil (plating layer and / or wiring pattern), fine wiring formability, 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 (1). It may be 8 parts by mass or less, or 6 parts by mass or less, depending on the application. The resin composition (1) in this embodiment may contain only one cyanate ester compound or may contain two or more cyanate ester compounds. When two or more cyanate ester compounds are contained, the total amount is preferably in the above range.

[0093] <<Phenol Compound>> The phenol compound is not particularly limited as long as it has two or more phenolic hydroxyl groups per molecule. Examples include phenols having two or more phenolic hydroxyl groups per molecule, bisphenols (e.g., bisphenol A, bisphenol E, bisphenol F, bisphenol S, etc.), diallyl bisphenols (e.g., diallyl bisphenol A, diallyl bisphenol E, diallyl bisphenol F, diallyl bisphenol S, etc.), phenol novolac resins (e.g., phenol novolac resin, naphthol novolac resin, cresol novolac resin, etc.), naphthalene phenolic resins, dihydroanthracene phenolic resins, dicyclopentadiene phenolic resins, biphenyl phenolic resins, and aralkyl phenolic resins. These phenolic compounds may be used alone or in combination of two or more. Among these, the phenolic compound preferably contains an aralkyl phenolic resin from the viewpoint of further improving copper foil adhesion.

[0094] <<<Aralkyl-Type Phenol Resin>>> Examples of the aralkyl-type phenol resin include compounds represented by formula (c2). (In formula (c2), Ar １ each independently represents a benzene ring or a naphthalene ring; Ar ２ represents a benzene ring, a naphthalene ring, or a biphenyl ring, and R ２ａ are each independently a hydrogen atom or a methyl group, and m is an integer of 1 to 50, and each ring may have a substituent other than a hydroxyl group. The substituent is, for example, an alkyl group having 1 to 5 carbon atoms or a phenyl group.

[0095] The compound represented by formula (c2) is, from the viewpoint of further improving the metal foil adhesion of the first insulating resin layer, １ is a naphthalene ring, and Ar ２ is a benzene ring (hereinafter also referred to as "naphthol aralkyl type phenolic resin"); and １ is a benzene ring, and Ar ２is a biphenyl ring (hereinafter also referred to as "biphenylaralkyl type phenolic resin").

[0096] The naphthol aralkyl phenol resin is preferably a compound represented by formula (2b).

[0097] (In formula (2b), R ２ａ each independently represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 10.

[0098] In formula (2b), R ２ａ preferably represents a hydrogen atom, and m preferably represents an integer of 1 to 6.

[0099] The biphenylaralkyl phenol resin is preferably a compound represented by formula (2c). (In formula (2c), R ２ｂ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group; m1 represents an integer of 1 to 20.

[0100] In formula (2c), R ２ｂ preferably represents a hydrogen atom, and m1 preferably represents an integer of 1 to 6.

[0101] The aralkyl phenol resin may be a commercially available product, or a product produced by a known method. Commercially available aralkyl phenol resins include "KAYAHARD GPH-65," "KAYAHARD GPH-78," and "KAYAHARD GPH-103" (biphenyl aralkyl phenol resins) manufactured by Nippon Kayaku Co., Ltd., and "SN-495" (naphthol aralkyl phenol resin) manufactured by Nippon Steel Chemical Co., Ltd.

[0102] When the resin composition (1) contains a phenolic compound, the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the resin solid content, and is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less. The resin composition (1) may contain only one type of phenolic compound, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0103] <<Other Thermosetting Compounds>> Examples of other thermosetting compounds include oxetane compounds, benzoxazine compounds, and compounds having a polymerizable unsaturated group. For details of these resins, see paragraphs 0135 to 0138 of WO 2020 / 022084, paragraphs 0036 to 0039 of WO 2023 / 013709, and paragraphs 0066 to 0069 and 0094 to 0106 of WO 2023 / 171553, the contents of which are incorporated herein by reference.

[0104] <<Silicone-Modified Thermosetting Compound>> The resin composition (1) may contain a silicone-modified thermosetting compound containing at least one group selected from the group consisting of a maleimide group, an amino group, an epoxy group, a carboxy group, a vinyl group, a hydroxy group, and a (meth)acrylic group, and a polysiloxane structure. The silicone-modified thermosetting compound preferably has a polysiloxane skeleton in which siloxane bonds are formed repeatedly in the molecule, and contains at least one group selected from the group consisting of a maleimide group, an amino group, an epoxy group, a carboxy group, a vinyl group, a hydroxy group, and a (meth)acrylic group.

[0105] <<<Epoxy-Modified Silicone>>> A first embodiment of the silicone-modified thermosetting compound is a silicone compound having an epoxy group (hereinafter, may be referred to as "epoxy-modified silicone"). The epoxy-modified silicone is not particularly limited as long as it is a silicone compound or resin modified with an epoxy group-containing group. By containing the epoxy-modified silicone, the resin composition (1) can exhibit excellent low thermal expansion properties and chemical resistance for the first insulating resin layer.

[0106] The polysiloxane structure may be a linear silicone structure, a cyclic silicone structure, or a network silicone structure. In this embodiment, a linear silicone structure is preferred.

[0107] The epoxy group-containing group is not particularly limited, but examples thereof include groups represented by the following formula (a1). (In formula (a1), R ０ represents an alkylene group (for example, an alkylene group having 1 to 5 carbon atoms, such as a methylene group, an ethylene group, or a propylene group), and X represents a monovalent group represented by the following formula (a2) or a monovalent group represented by the following formula (a3):

[0108] In formula (a1), the alkylene group is preferably an alkylene group having 1 to 5 carbon atoms, such as a methylene group, an ethylene group, or a propylene group. Preferred examples of the epoxy compound used in the epoxy-modified silicone include the epoxy compounds described above in the section "Epoxy Compounds."

[0109] The epoxy-modified silicone preferably contains an epoxy-modified silicone having an epoxy equivalent of 140 to 250 g / mol. By containing an epoxy-modified silicone having an epoxy equivalent within the above range, the epoxy-modified silicone tends to further improve compatibility with thermosetting compounds, low thermal expansion, and chemical resistance in a well-balanced manner. From the same viewpoint, the epoxy equivalent is more preferably 145 to 245 g / mol, and even more preferably 150 to 240 g / mol.

[0110] From the viewpoint of achieving a good balance between compatibility with thermosetting compounds, low thermal expansion, and chemical resistance, the epoxy-modified silicone preferably contains two or more types of epoxy-modified silicone. In this case, the two or more types of epoxy-modified silicone preferably have different epoxy equivalents, more preferably contain an epoxy-modified silicone having an epoxy equivalent of 50 to 350 g / mol and an epoxy-modified silicone having an epoxy equivalent of 400 to 4000 g / mol, and even more preferably contain an epoxy-modified silicone having an epoxy equivalent of 140 to 250 g / mol and an epoxy-modified silicone having an epoxy equivalent of 450 to 3000 g / mol.

[0111] When the epoxy-modified silicone contains two or more types of epoxy-modified silicone, the average epoxy equivalent of the epoxy-modified silicone is preferably 140 to 3,000 g / mol, more preferably 250 to 2,000 g / mol, and even more preferably 300 to 1,000 g / mol. The average epoxy equivalent is calculated using the following formula: (In the formula, Ei represents the epoxy equivalent of one of the two or more epoxy-modified silicones, Wi represents the proportion of the epoxy-modified silicone in the epoxy-modified silicone, and W1 + W2 + ... Wn = 1.)

[0112] The epoxy-modified silicone preferably contains the epoxy-modified silicone represented by formula (1) from the viewpoint of achieving a good balance between compatibility with the thermosetting compound, low thermal expansion, and chemical resistance. (In formula (1), R １ each independently represents an alkylene group, a phenylene group, or an aralkylene group; R ２ each independently represents an alkyl group having 1 to 10 carbon atoms or a phenyl group, and n represents an integer of 1 or more.

[0113] In formula (1), R １ each independently represents an alkylene group, a phenylene group, or an aralkylene group. １The alkylene group represented by the formula (I) may be linear, branched, or cyclic. The number of carbon atoms in the alkylene group is preferably 1 to 12, and more preferably 1 to 4. The alkylene group is not particularly limited, but examples thereof include a methylene group, an ethylene group, and a propylene group.

[0114] In formula (1), R １ The number of carbon atoms in the aralkylene group represented by formula (XI) is preferably 7 to 30, and more preferably 7 to 13. The aralkylene group is not particularly limited, but examples thereof include groups represented by formula (XI). (In formula (XI), * represents a bond.)

[0115] In formula (1), R １ The group represented by may further have a substituent, and examples of the substituent include a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, a linear alkoxy group having 1 to 10 carbon atoms, a branched alkoxy group having 3 to 10 carbon atoms, and a cyclic alkoxy group having 3 to 10 carbon atoms. Among these, R １ is particularly preferably a propylene group.

[0116] In formula (1), R ２ each independently represents an alkyl group having 1 to 10 carbon atoms or a phenyl group. The alkyl group and phenyl group may have a substituent. The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group is not particularly limited, but examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, an isobutyl group, and a cyclohexyl group. Among these, R ２ is preferably a methyl group or a phenyl group.

[0117] In formula (1), n ​​represents an integer of 1 or more, for example, 1 to 100. From the viewpoint of further improving compatibility with the thermosetting compound, low thermal expansion property, and chemical resistance in a well-balanced manner, n is preferably 50 or less, more preferably 30 or less, and even more preferably 20 or less.

[0118] From the viewpoint of further improving compatibility with thermosetting compounds, low thermal expansion, and chemical resistance in a well-balanced manner, the epoxy-modified silicone preferably contains two or more types of epoxy-modified silicones represented by formula (1). In this case, the two or more types of epoxy-modified silicones preferably have different n's, and it is more preferable to contain an epoxy-modified silicone in formula (1) where n is 1 to 2 and an epoxy-modified silicone in formula (1) where n is 5 to 20.

[0119] The average number of epoxy groups per molecule of the epoxy-modified silicone is preferably 1 or more and less than 3, and more preferably 1.5 or more and 2.5 or less. The average number of epoxy groups is calculated by the following formula. (In the formula, Bi represents the number of epoxy groups in the epoxy-modified silicone having i epoxy groups in the molecule, Yi represents the proportion of the epoxy-modified silicone having i epoxy groups in the molecule relative to the total epoxy-modified silicone, and Y1 + Y2 + ... Yn = 1.)

[0120] The epoxy-modified silicone may be an epoxy-modified silicone (hereinafter sometimes referred to as "epoxy-modified silicone (X1)") that contains a structural unit derived from an alkenylphenol, a structural unit derived from the epoxy-modified silicone, and a structural unit derived from an epoxy compound other than the epoxy-modified silicone. The epoxy-modified silicone (X1) may further contain a structural unit derived from a phenol compound other than an alkenylphenol, as necessary.

[0121] Preferred examples of alkenylphenols constituting structural units derived from alkenylphenols include the (meth)allylphenol compounds described above in the section <<(meth)allyl compounds>>. Preferred examples of phenol compounds constituting structural units derived from phenol compounds other than alkenylphenol-derived structural units include the phenol compounds described above in the section <<Phenol compounds>>.

[0122] The content of the alkenylphenol-derived structural unit, relative to the total mass of the epoxy-modified silicone (X1), is preferably 5 to 50 mass%, more preferably 10 to 45 mass%, and even more preferably 10 to 40 mass%. By having the content of this structural unit within this range, there is a tendency for even better compatibility with other thermosetting compounds to be exhibited.

[0123] The content of the structural unit derived from the epoxy-modified silicone is preferably 20 to 60 mass %, more preferably 25 to 55 mass %, and even more preferably 30 to 50 mass %, relative to the total mass of the epoxy-modified silicone (X1). When the content of this structural unit is within the above range, the first insulating resin layer tends to exhibit even better low thermal expansion and chemical resistance in a well-balanced manner.

[0124] The structural units derived from the epoxy-modified silicone are preferably structural units derived from an epoxy-modified silicone having an epoxy equivalent of 50 to 350 g / mol (hereinafter also referred to as a "low equivalent weight epoxy-modified silicone"), and an epoxy-modified silicone having an epoxy equivalent of 400 to 4000 g / mol (hereinafter also referred to as a "high equivalent weight epoxy-modified silicone").

[0125] The content of structural units derived from the low equivalent weight epoxy-modified silicone is preferably 5 to 25 mass%, more preferably 7.5 to 20 mass%, and even more preferably 10 to 17 mass%, relative to the total mass of the epoxy-modified silicone (X1).

[0126] The content of structural units derived from the high equivalent weight epoxy-modified silicone is preferably 15 to 55 mass %, more preferably 20 to 52.5 mass %, and even more preferably 25 to 50 mass %, relative to the total mass of the epoxy-modified silicone (X1).

[0127] Regarding epoxy-modified silicones, in addition to the above, the descriptions in paragraphs 0031 to 0044 and 0069 to 0088 of WO 2020 / 022084 and the descriptions in paragraphs 0128 to 0232 of WO 2023 / 013709 can be referred to, the contents of which are incorporated herein by reference.

[0128] <<<Amino-Modified Silicone>>> A second embodiment of the silicone-modified thermosetting compound is a compound having a structural unit derived from an amino-modified silicone and a structural unit derived from a maleimide compound (hereinafter, sometimes referred to as "amino-modified silicone"). The amino-modified silicone is preferably a polymer obtained by polymerizing an amino-modified silicone, a maleimide compound, and a carboxylic acid and / or a carboxylic acid anhydride. The amino-modified silicone will be described below.

[0129] In this specification, "structural units derived from amino-modified silicone" and "structural units derived from maleimide compounds" refer to structural units obtained by polymerizing the amino-modified silicone and maleimide compound components in the amino-modified silicone, as well as structural units formed by reactions that can give similar structural units. Hereinafter, in this specification, "structural units derived from ..." will be interpreted in the same way.

[0130] The content of structural units derived from the amino-modified silicone is preferably 5 to 70% by mass, more preferably 10 to 50% by mass, and even more preferably 15 to 45% by mass, relative to 100% by mass of all structural units in the amino-modified silicone.

[0131] The content of the structural units derived from the maleimide compound is preferably 30 to 95% by mass, more preferably 50 to 90% by mass, and even more preferably 55 to 85% by mass, relative to 100% by mass of all structural units in the amino-modified silicone.

[0132] The amine value of the amino-modified silicone is preferably 2.0 mgKOH / g or less, more preferably 1.0 mgKOH / g or less, and even more preferably 0.5 mgKOH / g or less. The amine value is the total amount of primary amines and secondary amines. When the amine value is 2.0 mgKOH / g or less, the increase in viscosity of the resin composition (1), the increase in molecular weight, the gelation of the varnish, and the increase in prepreg viscosity tend to be suppressed. Furthermore, the smaller the amine value, the more the increase in viscosity and the increase in molecular weight of the resin composition (1) tend to be suppressed. The lower limit of the amine value is preferably 0 mgKOH / g. The amine value is measured by a method in accordance with JIS K 7237:1995.

[0133] The weight-average molecular weight (Mw) of the amino-modified silicone is preferably 5,000 to 20,000, more preferably 10,000 to 15,000. A weight-average molecular weight of 5,000 or more tends to reduce the thermal expansion coefficient of the prepreg, while a weight-average molecular weight of 20,000 or less tends to suppress increases in viscosity and molecular weight of the resin composition (1), varnish gelation, and prepreg viscosity. The weight-average molecular weight of the amino-modified silicone can be adjusted to 5,000 to 20,000 by controlling the reaction conditions, such as temperature and time, during preparation of the amino-modified silicone. In this embodiment, the weight-average molecular weight can be measured by gel permeation chromatography (GPC) and calculated using a standard polystyrene calibration curve.

[0134] From the viewpoint of improving the reactivity between the components constituting the amino-modified silicone and the compatibility with other thermosetting compounds, the amino-modified silicone is preferably a polymer (hereinafter sometimes referred to as "polymer (B1)") obtained by polymerizing at least an amino-modified silicone, a maleimide compound, and a carboxylic acid and / or a carboxylic acid anhydride. The polymer (B1) contains at least a structural unit derived from the amino-modified silicone and a structural unit derived from the maleimide compound. With regard to the maleimide compound, the matters described in <<Maleimide compound>> that may be contained in the resin composition (1) can be taken into consideration, and the preferred range is also the same.

[0135] The amino-modified silicone is not particularly limited as long as it is a silicone having one or more amino groups in the molecule, but it is preferably a silicone having two or more amino groups in the molecule, and more preferably contains an amino-modified silicone represented by formula (1). By containing a structural unit derived from the amino-modified silicone, the amino-modified silicone or polymer (B1) can exhibit excellent compatibility with other thermosetting compounds. The amino-modified silicones can be used alone or in appropriate combination of two or more.

[0136]

[0137] In formula (1), R ａ R each independently represents a hydrogen atom, an alkyl group, or a phenyl group. ｂ each independently represents a single bond, an alkylene group, or an arylene group, and n represents an integer of 1 to 100.

[0138] Examples of the alkyl group include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, and branched alkyl groups such as isopropyl, isobutyl, and tert-butyl groups. Of these, a methyl group is preferred.

[0139] R ｂ is preferably an alkylene group. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, and a tetramethylene group. The alkylene group more preferably has 1 to 4 carbon atoms in the main chain, and is even more preferably a trimethylene group.

[0140] Examples of arylene groups include phenyl, naphthyl, indenyl, biphenyl, and anthryl groups.

[0141] The amino group equivalent of the amino-modified silicone is preferably 130 to 6000 g / mol, more preferably 500 to 3000 g / mol, and even more preferably 600 to 2500 g / mol. The amino group equivalent is measured by a method in accordance with JIS K 7237:1995.

[0142] The amino-modified silicone may be a commercially available product, or a product produced by a known method. Commercially available amino-modified silicones include "X-22-161A" (amino group equivalent: 800 g / mol), "X-22-161B" (amino group equivalent: 1500 g / mol), and "KF-8010" (amino group equivalent: 430 g / mol), all manufactured by Shin-Etsu Chemical Co., Ltd.

[0143] The carboxylic acid used in the production of the polymer (B1) is not particularly limited, but is preferably at least one selected from the group consisting of maleic acid, phthalic acid, succinic acid, acetic acid, and propionic acid, more preferably at least one selected from the group consisting of maleic acid, phthalic acid, succinic acid, and acetic acid, and even more preferably at least one selected from the group consisting of maleic acid, phthalic acid, and succinic acid. The carboxylic acid anhydride is not particularly limited, but is preferably at least one selected from the group consisting of maleic anhydride, phthalic anhydride, succinic anhydride, acetic anhydride, and propionic acid, more preferably at least one selected from the group consisting of maleic anhydride, phthalic anhydride, succinic anhydride, and acetic anhydride, and even more preferably at least one selected from the group consisting of maleic anhydride, phthalic anhydride, succinic anhydride, and acetic anhydride.

[0144] Among these, a monocarboxylic acid and / or a monocarboxylic anhydride, or a dicarboxylic acid and / or a dicarboxylic anhydride is preferred, and a dicarboxylic acid and / or a dicarboxylic anhydride is more preferred. When the carboxylic acid and / or the carboxylic anhydride is a dicarboxylic acid and / or a dicarboxylic anhydride, respectively, the effects of the present embodiment tend to be more effectively improved compared to when a monocarboxylic acid and / or a monocarboxylic anhydride is used.

[0145] The carboxylic acids and carboxylic anhydrides may be used singly or in appropriate combination of two or more. The carboxylic acids and carboxylic anhydrides may be used singly or in combination.

[0146] In this embodiment, using only a carboxylic acid anhydride is preferable compared to using only a carboxylic acid. Since carboxylic acid anhydrides have superior reactivity, they tend to be able to favorably suppress the reactivity of the polymer (B1) by reacting with amino groups in the polymer (B1). As a result, the storage stability of the resin composition (1) and prepreg containing the polymer (B1) is excellent (for example, suppression of an increase in the viscosity of the resin composition (1), an increase in molecular weight, gelation of the varnish, and an increase in the viscosity of the prepreg, etc.), and they also tend to be excellent in moldability when mixed with other thermosetting compounds.

[0147] The content of structural units derived from amino-modified silicone in polymer (B1) is preferably 15 to 60 mass%, more preferably 20 to 55 mass%, and even more preferably 30 to 50 mass%, relative to 100 mass% of all structural units in polymer (B1).

[0148] The content of the structural units derived from a maleimide compound in the polymer (B1) is preferably 35 to 75% by mass, more preferably 40 to 70% by mass, and even more preferably 44 to 65% by mass, relative to 100% by mass of all structural units in the polymer (B1).

[0149] The content (total content) of structural units derived from carboxylic acid and / or carboxylic acid anhydride in polymer (B1) is preferably 0.1 to 10 mass%, more preferably 0.5 to 7 mass%, and even more preferably 1 to 6 mass%, relative to 100 mass% of all structural units in polymer (B1).

[0150] Regarding the epoxy-modified silicone, in addition to the above, the description in paragraphs 0075 to 0127 of WO 2023 / 013709 can be referred to, the contents of which are incorporated herein by reference.

[0151] <<BT Resin>> BT resin is a polymer of a cyanate ester compound and a maleimide compound. The polymerization may be performed without a solvent, or by dissolving the compounds in a solvent (e.g., ethyl ethyl ketone, N-methylpyridin, dimethylformamide, dimethylacetamide, toluene, or xylene) and mixing them under heating.

[0152] The cyanate ester compound used in the synthesis of the BT resin is not particularly limited, and the cyanate ester compounds described above in the section <<Cyanate ester compounds>> are preferred.

[0153] The maleimide compound used in the synthesis of the BT resin is not particularly limited, and the maleimide compounds described above in the section "Maleimide Compounds" are preferred.

[0154] The proportion of the cyanate ester compound in the BT resin is not particularly limited, but is preferably in the range of 25 to 95 mass %, more preferably 30 to 90 mass %, relative to the total amount of BT resin. The proportion of the maleimide compound in the BT resin is not particularly limited, but from the viewpoints of the glass transition temperature, flame retardancy, and curability of the first insulating resin layer, is preferably in the range of 5 to 75 mass %, more preferably 10 to 70 mass %, relative to the total amount of BT resin. Furthermore, the BT resin is usually a prepolymer, and its number average molecular weight is preferably in the range of 100 to 100,000.

[0155] Regarding BT resin, in addition to the above, the description in paragraphs 0055 to 0057 of Japanese Patent No. 6414799 can be referred to, the contents of which are incorporated herein by reference.

[0156] When the resin composition (1) contains a BT resin, the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the resin solid content, and is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less. The resin composition (1) may contain only one type of BT resin, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0157] <<Filler>> The resin composition (1) 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 (1) 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 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 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.

[0158] The filler used in this embodiment is not particularly limited in type, and can suitably be used by those skilled in the art.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 first insulating resin layer, such as heat resistance, dielectric properties, thermal expansion properties, dimensional stability, and flame retardancy, are further improved.

[0159] The content of the filler in the resin composition (1) can be appropriately set according to 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 (1). By setting the content of the filler at or above the lower limit, the heat resistance, low thermal expansion, and dielectric loss tangent of the first insulating resin layer 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 (1). By setting the content of the filler at or below the upper limit, the moldability of the first insulating resin layer tends to be further improved. In the resin composition (1), 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 (1) 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.

[0160] When a filler, particularly an inorganic filler, is used in the resin composition (1), a silane coupling agent may be further contained. 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 is preferably 0.1 to 10 parts by mass per 100 parts by mass of the resin solid content in the resin composition (1).

[0161] <<Flame Retardant>> The resin composition (1) may contain a flame retardant. Examples of the flame retardant include phosphorus-based flame retardants, halogen-based flame retardants, inorganic flame retardants, and silicone-based flame retardants, with phosphorus-based flame retardants being preferred. Known flame retardants can be used, including, for example, halogen-based flame retardants such as brominated epoxy resin, brominated polycarbonate, brominated polystyrene, brominated styrene, brominated phthalimide, tetrabromobisphenol A, pentabromobenzyl (meth)acrylate, pentabromotoluene, tribromophenol, hexabromobenzene, decabromodiphenyl ether, bis-1,2-pentabromophenylethane, chlorinated polystyrene, and chlorinated paraffin; red phosphorus; tricresyl phosphate; triphenyl phosphate; cresyl diphenyl phosphate; trixylenyl phosphate; and Examples of suitable flame retardants include phosphorus-based flame retardants such as phosphate, trialkyl phosphate, dialkyl phosphate, tris(chloroethyl)phosphate, phosphazene, 1,3-phenylenebis(phenyl phosphate), 1,3-phenylenebis(2,6-dixylenyl phosphate), and 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide; inorganic flame retardants such as aluminum hydroxide, magnesium hydroxide, partial boehmite, boehmite, zinc borate, and antimony trioxide; and silicone-based flame retardants such as silicone rubber and silicone resin. In this embodiment, among these, 1,3-phenylenebis(2,6-dixylenyl phosphate) is preferred because it does not impair the low dielectric properties (Dk and / or Df).

[0162] When the resin composition (1) contains a flame retardant, the content thereof is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition (1). Depending on the application, it may be 12 parts by mass or more. The lower limit of the content of the flame retardant 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. Depending on the application, it may be 20 parts by mass or less, 15 parts by mass or less. The flame retardant can be used alone or in combination of two or more. When two or more types are used, the total amount is within the above range.

[0163] <<Active Ester Compound>> The resin composition (1) 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.

[0164] When the resin composition (1) 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 (1). The resin composition (1) 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 within the above range. Furthermore, the resin composition (1) 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 (1).

[0165] <<Dispersant>> The resin composition (1) may contain a dispersant. As the dispersant, those generally used for paints can be suitably used, and the type thereof 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.

[0166] When the resin composition (1) contains a dispersant, the lower limit of the content thereof 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 (1). 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 (1). The dispersant 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.

[0167] <<Curing Accelerator>> The resin composition (1) 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 (for example, azobisisobutyronitrile); N,N-dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethyltoluidine, 2-N-ethylanilinoethanol, and the like. 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.

[0168] When the resin composition (1) contains a curing accelerator, the lower limit of its 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, relative to 100 parts by mass of the resin solid content in the resin composition (1). The upper limit of the content of the curing accelerator 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 even more preferably 1.0 parts by mass or less, 0.8 parts by mass or less, or 0.7 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition (1). The curing accelerator can be used alone or in combination of two or more types. When two or more types are used, the total amount is within the above range.

[0169] <<Solvent>> The resin composition (1) may contain a solvent, and preferably contains an organic solvent. When a solvent is contained, the resin composition (1) is in a form (solution or varnish) in which at least a portion, preferably all, of the various resin solids 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 solids 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.

[0170] <<Other Resin Additive Components>> In addition to the above components, the resin composition (1) may contain various polymer compounds such as elastomers, styrene-based oligomers, and thermoplastic resin oligomers, as well as 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, quinones, phenol-based, nitroso-, and hydroxyamine-based polymerization inhibitors. These additives may be used alone or in combination of two or more.

[0171] <Fiber Substrate> The first insulating resin layer preferably includes a fiber substrate. The fiber substrate is a substrate formed from fibers, and is preferably a substrate (prepreg substrate) for the first insulating resin layer, with glass cloth being preferred. The glass cloth is preferably a substrate formed from glass fibers (e.g., E-glass, D-glass, L-glass, S-glass, T-glass, Q-glass, UN-glass, NE-glass, NER-glass). The form of the fiber substrate is not particularly limited, and examples include woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat. These fiber substrates may be used alone or in combination of two or more. Among these fiber substrates, woven fabrics that have been subjected to an ultra-opening treatment and a clogging treatment are preferred from the viewpoint of dimensional stability, and the fiber substrate should preferably have a thickness of 200 μm or less and a mass of 250 g / m from the viewpoint of strength and low water absorbency. ２The following glass woven fabrics are preferred, and from the viewpoint of moisture absorption and heat resistance, glass woven fabrics surface-treated with epoxy silane, amino silane, or the like are 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 low-dielectric-constant fiber substrates include fiber substrates having a relative dielectric constant of 5.0 or less (preferably, 3.0 to 4.9). Examples of low-dielectric-tangent fiber substrates include fiber substrates having 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. In addition, in this embodiment, fiber substrates other than glass, such as inorganic fibers (e.g., quartz) and organic fibers (e.g., polyimide, polyamide, polyester, liquid crystal polyester, polytetrafluoroethylene, etc.), can also be used as the fiber substrate depending on the application.

[0172] <Second Insulating Resin Layer> The second insulating resin layer of this embodiment is not particularly limited as long as the dielectric loss tangent of the second insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator is lower than the dielectric loss tangent of the first insulating resin layer at a frequency of 10 GHz measured using a perturbation cavity resonator. The second insulating resin layer is typically formed from a resin composition (2) containing a thermosetting compound. Preferably, the second insulating resin layer does not typically contain a fiber substrate (particularly glass cloth). In the layer formed from the resin composition (2), the resin solid content contained in the resin composition (2) may be in an uncured, semi-cured, or cured state. Preferably, the resin solid content contained in the resin composition (2) is in a semi-cured or cured state.

[0173] The type and the like of the thermosetting compound contained in the resin composition (2) are not particularly specified, but it is preferable that the thermosetting compound contains at least one selected from the group consisting of maleimide compounds, cyanate ester compounds, polyphenylene ether compounds having a terminal carbon-carbon unsaturated double bond, 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. (In formula (V), Ar represents an aromatic hydrocarbon linking group. * represents a bonding position.)

[0174] <<Maleimide Compound>> The resin composition (2) may contain a maleimide compound. The resin composition (2) 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 still 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), and 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), and it is even more preferable that the maleimide compound contains a compound represented by formula (M1) and / or a compound represented by formula (M3). When used in materials for printed wiring boards (e.g., metal foil-clad laminates), etc., excellent heat resistance can be imparted.

[0175] (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, the following compounds are preferred examples of formula (M0). 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.

[0176] 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.

[0177] (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.

[0178] 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 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, 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 (2) 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 (2) 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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 resin 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 resin layer) tend to be further improved.

[0185] 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 resin layer) tends to have further improved low dielectric properties, low water absorption, heat resistance, and handleability.

[0186] 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 resin layer) tends to have further improved low dielectric properties, low water absorbency, heat resistance, and handleability.

[0187] 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.

[0188] (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.

[0189] (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.

[0190] (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 each preferably 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.

[0191] (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 The compound represented by formula (M0) may be a mixture of compounds having different moieties, and is preferably a mixture. As described in the compound represented by formula (M0), the compound may be a mixture of compounds having different moieties.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] When the resin composition (2) contains a maleimide compound, the lower limit of the content thereof 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 (2), and may be 20 parts by mass or more, 30 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 heat resistance of the second insulating resin 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 may even be 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 (2). 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 of the second insulating resin layer tend to be improved. The resin composition (2) in this embodiment may contain only one maleimide compound or may contain two or more maleimide compounds. When two or more maleimide compounds are contained, the total amount is preferably in the above range.

[0201] <<Cyanate Ester Compound>> The resin composition (2) preferably contains a cyanate ester compound. By including a cyanate ester compound in the resin composition (2), the adhesion between the insulating resin layer and the metal foil (plating 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). As the cyanate ester compound, those described in the resin composition (1) can be preferably used, more preferably a naphthol aralkyl cyanate ester compound, and even more preferably a cyanate cyanate ester compound represented by formula (5).

[0202] When the resin composition (2) 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 (2). When the cyanate ester compound content is 0.1 parts by mass or more, the second insulating resin layer tends to have excellent adhesion to the metal foil (plating layer and / or wiring pattern), fine wiring formability, 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 (2). It may be 8 parts by mass or less, or 6 parts by mass or less, depending on the application. The resin composition (2) in this embodiment may contain only one cyanate ester compound or may contain two or more cyanate ester compounds. When two or more cyanate ester compounds are contained, the total amount is preferably in the above range.

[0203] <<Polyphenylene Ether Compound Having a Terminal Carbon-Carbon Unsaturated Double Bond>> The resin composition (2) preferably contains a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond. By including a polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond in the resin composition (2), the adhesion between the insulating resin layer and the metal foil (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 resin layer and the metal foil (plating 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.

[0204] 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):

[0205] (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.

[0206] 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 ３５ may 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.

[0207] 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)"). 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 is more preferred, and a modified polyphenylene ether compound having two or more terminal groups selected from the group consisting of (meth)acryloyl groups and vinylbenzyl groups is even more preferred. The use of such a modified polyphenylene ether compound (g) not only improves the adhesion between the insulating resin layer and the metal foil (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 (2) and enhances its low water absorption. The modified polyphenylene ether compounds (g) may be used singly or in combination of two or more.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] (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).

[0221] 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.

[0222] 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.)

[0223] 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.

[0224] 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.

[0225] 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 (2) 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 (2) tends to be lower. By setting the content at or below the upper limit, the solubility, low viscosity, and moldability of the resin composition (2) 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 (2) tends to be further lower. By setting the content at or below the upper limit, the solubility, low viscosity, and moldability of the resin composition (2) in solvents tend to be further improved.

[0226] When the resin composition (2) 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 (2). By setting the content at or above the lower limit, adhesion between the second insulating resin layer and the metal foil (plating layer and / or wiring pattern) and fine wiring formability are further improved, and low dielectric properties (Dk and / or Df) and moisture absorption heat resistance 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 (2). By setting the content to the above upper limit or less, the adhesion, heat resistance, and chemical resistance between the second insulating resin layer and the metal layer (plating layer and / or wiring pattern) tend to be better. The resin composition (2) in this embodiment may contain only one polyphenylene ether compound having a terminal carbon-carbon unsaturated double bond, or may contain two or more polyphenylene ether compounds. When two or more polyphenylene ether compounds are contained, the total amount is preferably within the above range.

[0227] <<Compound Having an Indane Skeleton with a Terminal Carbon-Carbon Unsaturated Double Bond>> The resin composition (2) 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. ｙrepresents 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.)

[0228] 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.

[0229] 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.

[0230] <<Compound Having a Vinylene Group>> The resin composition (2) 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 compounds containing one -CH=CH- group in the molecule are preferred. Furthermore, compounds having a vinylene group that also fall under the category of maleimide compounds are referred to as maleimide compounds. Specific examples of compounds having a vinylene group include preferred acenaphthylene and pyracylene, and more preferred acenaphthylene. In this specification, compounds that also fall under the category of 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 fall under the category of compounds having a vinylene group.

[0231] 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.

[0232] The content of the polymer having a structural unit represented by formula (V) in the resin composition (2) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition (2). Depending on the intended use, it may be 15 parts by mass or more, 20 parts by mass or more, 25 parts by mass or more, or 30 parts by mass or more. By setting the content of the polymer having a structural unit represented by formula (V) to the above-mentioned lower limit or more, the low dielectric properties and low water absorption of the second insulating resin layer tend to be further improved. Furthermore, the upper limit of the content of the polymer having a structural unit represented by formula (V) is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the resin solid content in the resin composition (2). Depending on the intended use, it may be 30 parts by mass or less, or 20 parts by mass or less. By setting the content of the thermosetting compound to the above-mentioned upper limit or less, the heat resistance, plating adhesion, low thermal expansion, etc. of the insulating resin layer of the second insulating resin layer tend to be further improved. The resin composition (2) may contain only one polymer having a structural unit represented by formula (V), or may contain two or more polymers. When two or more polymers are contained, the total amount is preferably in the above range.

[0233] The total amount of thermosetting compounds in resin composition (2) is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, per 100 parts by mass of the resin solid content in resin composition (2). By setting the content of thermosetting compounds at or above the lower limit, the heat resistance and plating adhesion of the second insulating resin layer tend to be further improved. The upper limit of the content of thermosetting compounds 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 resin composition (2). Depending on the application, it may be 80 parts by mass or less, or 70 parts by mass or less. Setting the content of thermosetting compounds at or below the upper limit tends to further improve the low dielectric properties and low water absorption of the second insulating resin layer. The resin composition (2) may contain only one type of thermosetting compound, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0234] <<Elastomer>> The resin composition (2) 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.

[0235] 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 resin 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 this upper limit tends to improve the solubility of the elastomer component in the resin composition (2). When the resin composition (2) contains two or more elastomers, it is preferable that the number-average molecular weight of the mixture thereof falls within the above range.

[0236] 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.

[0237] 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.

[0238] 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.

[0239] 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.

[0240] 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 Fibers Corporation.

[0241] 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.

[0242] 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.

[0243] 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 resin layer) are more excellent.

[0244] 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 (2). 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 standpoints of availability and productivity. Of these, styrene is particularly preferred. The content of the styrene monomer unit in the thermoplastic elastomer (E) is preferably in the range of 10 to 50% by mass, more preferably 13 to 45% by mass, and even more preferably 15 to 40% by mass, of the total monomer units. A styrene monomer unit content of 50% by mass or less improves adhesion and tackiness to fibrous substrates and the like. Furthermore, if the content is 10% by mass or more, adhesion can be suppressed, adhesive residue and stop marks are less likely to occur, and 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 WO 2017 / 126469, the contents of which are incorporated herein by reference. The same applies to conjugated diene monomer units, etc., which will be described later.

[0245] 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 the resin composition (2). 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.

[0246] 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.

[0247] 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.

[0248] 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.

[0249] 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%.

[0250] 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.

[0251] 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.

[0252] When the resin composition (2) 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, and may even be 12 parts by mass or more, relative to 100 parts by mass of the resin solid content in the resin composition (2). By setting the content at or above the lower limit, the dielectric properties (low dielectric tangent) of the second insulating resin layer 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, even 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 (2). By setting the content at or below the upper limit, the heat resistance of the second insulating resin layer tends to be further improved. The resin composition (2) 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.

[0253] <<Styrene-Based Oligomer>> The resin composition (2) can also be used in combination with 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.

[0254] 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.

[0255] When the resin composition (2) 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 more preferably 5 parts by mass or more, per 100 parts by mass of the resin solid content in the resin composition (2). By setting the content at or above the lower limit, the low dielectric properties (Dk and / or Df) of the resulting cured product (insulating resin 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 (2). 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 resin layer) tend to be further improved. The resin composition (2) 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.

[0256] <<Filler>> The resin composition (2) may contain a filler. By containing 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 (2) and its cured product can be further improved. The filler that may be contained in the resin composition (2) is synonymous with the filler that may be contained in the resin composition (1), and the preferred range is also the same.

[0257] The content of the filler in the resin composition (2) can be appropriately set according to the desired properties and is not particularly limited. However, it is preferably 0 parts by mass or more, more 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, relative to 100 parts by mass of the resin solid content in the resin composition (1). By setting the content of the filler to the above lower limit or more, the heat resistance, low thermal expansion, and dielectric loss tangent of the first insulating resin layer tend to be further improved. Furthermore, the upper limit of the content of the filler is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 150 parts by mass or less, even more preferably 120 parts by mass or less, and may be 50 parts by mass or less, or 20 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition (1). By setting the content of the filler to the above upper limit or less, the moldability of the first insulating resin layer tends to be further improved. In the resin composition (2), as an example of a preferred embodiment, the content of the filler is 30% to 90% by mass of the components excluding the solvent. In another example of a preferred embodiment, in the resin composition (2), the content of the filler is 0 to 50% by mass (preferably 0 to 45% by mass, more preferably 0 to 40% by mass) of the mass of the resin solids. The resin composition (2) 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.

[0258] <<Flame Retardant>> The resin composition (2) may contain a flame retardant. Examples of flame retardants include phosphorus-based flame retardants, halogen-based flame retardants, inorganic flame retardants, and silicone-based flame retardants, with phosphorus-based flame retardants being preferred. The flame retardant that may be contained in the resin composition (2) is synonymous with the flame retardant that may be contained in the resin composition (1), and the preferred range (including the preferred content) is also the same.

[0259] <<Active Ester Compound>> The resin composition (2) may contain an active ester compound. The active ester compound that may be contained in the resin composition (2) has the same meaning as the active ester compound that may be contained in the resin composition (1), and the preferred range (including the preferred content) is also the same.

[0260] <<Dispersant>> The resin composition (2) may contain a dispersant. The dispersant that may be contained in the resin composition (2) has the same meaning as the dispersant that may be contained in the resin composition (1), and the preferred range (including the preferred content) is also the same.

[0261] <<Curing Accelerator>> The resin composition (2) may further contain a curing accelerator. The curing accelerator that may be contained in the resin composition (2) has the same meaning as the curing accelerator that may be contained in the resin composition (1), and the preferred range (including the preferred content) is also the same.

[0262] <<Solvent>> The resin composition (2) may contain a solvent, and preferably contains an organic solvent. The solvent that may be contained in the resin composition (2) has the same meaning as the solvent that may be contained in the resin composition (1), and the preferred range (including the preferred content) is also the same.

[0263] <<Other Resin Additive Components>> In addition to the above components, the resin composition (2) may contain various polymer 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 adjusters, lubricants, antifoaming agents, leveling agents, gloss agents, quinones, phenolic, nitroso, and hydroxyamine-based polymerization inhibitors. These additives can be used alone or in combination of two or more.

[0264] <Metal Foil> The multilayer body of this embodiment may have a metal foil. That is, the multilayer body of this embodiment may be a metal foil-clad laminate (sometimes referred to as a metal foil-clad laminate). That is, an example is a mode in which a metal foil is provided on the surface of the first insulating resin layer and / or the second insulating resin layer. More specifically, an example is a multilayer body in which a metal foil is further arranged so as to contact the surface of the second insulating resin layer opposite the first insulating resin layer. Another example is a multilayer body in which a metal foil is further arranged so as to contact the surface of the second insulating resin layer opposite the first insulating resin layer.

[0265] The metal foil is preferably one used as a material for printed wiring boards, such as rolled copper foil or electrolytic copper foil. The thickness of the metal foil (preferably, copper foil) is not particularly limited and may be approximately 1.5 to 70 μm. Furthermore, the metal foil (preferably, copper foil) preferably has a surface roughness Rz of 0.2 to 4.0 μm, as measured in accordance with JIS B0601:2013. By adjusting the surface roughness Rz of the metal foil (preferably, copper foil) to 0.2 μm or more, the surface roughness of the metal foil (preferably, copper foil) becomes appropriate, and the peel strength of the metal foil (preferably, copper foil) tends to be further improved. On the other hand, by adjusting the surface roughness Rz of the metal foil (preferably, copper foil) to 4.0 μm or less, the surface roughness of the metal foil (preferably, copper foil) becomes appropriate, and the dielectric loss tangent characteristics of the resulting cured product tend to be further improved. From the viewpoint of the dielectric loss tangent characteristics and copper foil peel strength of the cured product to be obtained, the surface roughness Rz of the metal foil (preferably copper foil) is more preferably 0.5 μm or more, even more preferably 0.6 μm or more, particularly preferably 0.7 μm or more, and more preferably 3.5 μm or less, even more preferably 3.0 μm or less, particularly preferably 2.0 μm or less. In particular, it is preferable that the metal foil (preferably copper foil) provided on the surface of the second insulating resin layer satisfies the above Rz.

[0266] The multilayer body of this embodiment can be suitably used as a low dielectric constant material and / or a low dielectric loss tangent material, such as an insulating resin layer for a printed wiring board, a material for a semiconductor package, or a resin composition for electronic materials. The multilayer body of this embodiment can be suitably used as a material for a metal foil-clad laminate, a resin composite sheet, and a printed wiring board. Therefore, this embodiment discloses a printed wiring board including the multilayer body of this embodiment. Also, this embodiment discloses a semiconductor device including the printed wiring board of this embodiment.

[0267] <Method for manufacturing a multilayer body> Next, a method for manufacturing a multilayer body of this embodiment will be described. The method for manufacturing a multilayer body of this embodiment includes bonding a second insulating resin layer and a first insulating resin layer. In the method for manufacturing a multilayer body of this embodiment, it is preferable to bond a first insulating resin layer in a cured state and a second insulating resin layer in a semi-cured state. By bonding them in this manner, the two layers (their materials) are less likely to mix with each other, and transmission loss can be more effectively reduced. On the other hand, it is also preferable to bond the first insulating resin layer and the second insulating resin layer in a semi-cured state. By bonding them in this manner, it is possible to simplify the process.

[0268] An example of a method for producing a multilayer body according to this embodiment includes joining the second insulating resin layer side of a second insulating resin layer having a metal foil on one surface to a first insulating resin layer. The second insulating resin layer having a metal foil on one surface is preferably obtained by removing one of the metal foils from a metal foil-attached second insulating resin layer having metal foils on both surfaces of the second insulating resin layer. Alternatively, the second insulating resin layer having a metal foil on one surface is also preferably obtained by removing the protective film from a metal foil-attached second insulating resin layer having a metal foil on one surface and a protective film on the other surface. The protective film is preferably a thermoplastic resin film, more preferably a polyethylene terephthalate resin film.

[0269] Furthermore, the first insulating resin layer is preferably obtained by removing at least one of the metal foils from a metal foil-covered first insulating resin layer having metal foils on both surfaces of the first insulating resin layer. Alternatively, the first insulating resin layer may be a prepreg, and the second insulating resin layer side of a second insulating resin layer having metal foil on one surface thereof may be bonded to at least one surface (or both surfaces) of the prepreg.

[0270] A method for manufacturing the multilayer body of this embodiment will be described below with reference to Fig. 4. It goes without saying that the multilayer body of this embodiment is not limited to the form shown in Fig. 4. In Fig. 4, the same components as in Figs. 1 to 3 are designated by the same reference numerals. In Fig. 4, for convenience, the metal foil of the metal foil-clad insulating resin layer that is peeled off during the manufacturing process of the multilayer body is designated by reference numeral 41. However, it goes without saying that the metal foil designated by reference numeral 4 may also be peeled off depending on the application of the multilayer body, etc.

[0271] In the multilayer structure of this embodiment, the metal foils 41 on both surfaces of the metal-foil-clad first insulating resin layer 7, which has the metal foil 41 on both surfaces of the first insulating resin layer 2, are typically removed (see FIG. 4A). Also, one of the metal foils 41 on the metal-foil-clad second insulating resin layer 3, which has the metal foil 4 on both surfaces of the second insulating resin layer 3, is typically removed (not shown). Next, the second insulating resin layer side of the second insulating resin layer 3, which has the metal foil 4 on one surface, is bonded to the first insulating resin layer 2 from which the metal foil 41 has been removed (see FIG. 4B). In this manner, it is preferable to manufacture the first insulating resin layer 2 as a metal foil-clad laminate, remove the metal foils 41 from the first insulating resin layer 2, and then bond the second insulating resin layer 3 and the first insulating resin layer 2 together. This configuration allows the second insulating resin layer 3 to be bonded in a semi-cured state, preventing the two materials from intermixing, thereby more effectively reducing transmission loss. In the step shown in FIG. 4B , the second insulating resin layer 3 is bonded to both surfaces of the first insulating resin layer 2, respectively. However, the second insulating resin layer 3 may be bonded to only one surface of the first insulating resin layer 2. Furthermore, when the second insulating resin layer 3 is bonded to only one surface of the first insulating resin layer 2, only the metal foil 41 on one surface of the first insulating resin layer 2 may be removed. In the multilayer body of this embodiment, the step of removing the metal foil 41 from the metal-foil-attached first insulating resin layer 7, which has the metal foil 41 on both surfaces of the first insulating resin layer 2, and the step of removing the metal foil from the metal-foil-attached second insulating resin layer (not shown), which has the metal foil 4 on both surfaces of the second insulating resin layer 3, may be performed simultaneously, or either may be performed first. The metal foil is preferably removed by etching.

[0272] Furthermore, a metal foil-covered second insulating resin layer having a metal foil on one surface and a protective film on the other surface may be used instead of the metal foil-covered second insulating resin layer 3 having the metal foils 4, 41 on both surfaces of the second insulating resin layer 3. In this case, it is preferable to peel off the protective film and bond it to the first insulating resin layer.

[0273] In addition, the first insulating resin layer 2 and the second insulating resin layer 3 are preferably bonded together by arranging them so that their surfaces are in contact with each other. Examples of bonding methods include lamination molding using a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like at a temperature of about 180 to 350°C, a heating time of about 100 to 300 minutes, and a surface pressure of about 1 to 10 MPa.

[0274] Of course, the multilayer body of this embodiment may be obtained by a method other than the above. For example, another preferred example of a method for producing the multilayer body of this embodiment is to bond a second insulating resin layer that is a prepreg to a first insulating resin layer that is also a prepreg. In this case, the bonding method can also be a laminate molding method using a multistage press, a multistage vacuum press, a continuous molding machine, an autoclave molding machine, or the like, at a temperature of about 180 to 350°C, a heating time of about 100 to 300 minutes, and a surface pressure of about 1 to 10 MPa.

[0275] In the manufacturing method of the multilayer body of this embodiment, it is also preferable to form metal wiring 5 on the surface of the second insulating resin layer 3, as shown in FIG. 2 above. By forming metal wiring 5 on the surface of the second insulating resin layer 3 in this manner, the multilayer body of this embodiment is preferably used as a printed wiring board. That is, it is preferable that a circuit be formed or an element be mounted on the second insulating resin layer 3 side of the multilayer body of this embodiment. That is, it is preferable that the multilayer body of this embodiment has an outer layer circuit and / or element provided on the surface of the second insulating resin layer. It is also preferable to form a third insulating resin layer 6 on the surface of the metal wiring 5, as shown in FIG. 3 above. This configuration results in a printed wiring board in which a metal circuit is embedded in the insulating resin layer. The metal wiring is preferably copper wiring and is drawn according to a known method. The third insulating resin layer is similar to the matters described in the section on the second insulating resin layer, and the preferred ranges are also similar. The second insulating resin layer and the third insulating resin layer may be the same or different. In either case, it is preferable that the third insulating resin layer is a layer formed from the resin composition (2). More specifically, an inner layer circuit is formed on the surface of the multilayer body of this embodiment, and this circuit is blackened to form an inner layer circuit. Then, the inner layer circuit and the multilayer body of this embodiment are alternately arranged one by one, and copper foil is further arranged as the outermost layer, and the laminate is molded under the above conditions, preferably in a vacuum, to produce a multilayer body. The method for producing a multilayer body of this embodiment can be suitably used as a method for producing a printed wiring board.

[0276] This embodiment also relates to a semiconductor device including the printed wiring board. For details of the semiconductor device, please refer to paragraphs 0200 to 0202 of Japanese Patent Laid-Open No. 2021-021027, the contents of which are incorporated herein by reference.

[0277] 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.

[0278] Synthesis Example 1: Synthesis of α-naphthol aralkyl cyanate ester compound (SNCN) 0.47 mol (OH group equivalent) of α-naphthol aralkyl resin (SN495V, OH group equivalent: 236 g / eq., manufactured by Nippon Steel Chemical Co., Ltd.; the number of naphthol aralkyl repeating units included is 1 to 5) was dissolved in 500 mL of chloroform, and 0.7 mol of triethylamine was added to this solution to prepare solution 1. While maintaining the temperature at −10° C., solution 1 was added dropwise over 1.5 hours to 300 g of a chloroform solution of 0.93 mol of cyanogen chloride placed in a reactor, and after the addition was completed, the mixture was stirred for 30 minutes. Thereafter, a mixed solution of 0.1 mol of triethylamine and 30 g of chloroform was added dropwise to the reactor, and the mixture was stirred for 30 minutes to complete the reaction. The by-product triethylamine hydrochloride was filtered off from the reaction solution, and the resulting filtrate was washed with 500 mL of 0.1 N hydrochloric acid, followed by washing with 500 mL of water four times. The filtrate was dried over sodium sulfate, evaporated at 75°C, and further degassed under reduced pressure at 90°C to obtain a brown solid α-naphthol aralkyl cyanate ester compound represented by formula (S1) (R Ｃ１ ~R Ｃ４ are all hydrogen atoms, and n ｃ is a mixture of 1 to 5.) (cyanate equivalent: 261 g / eq.) was obtained. The obtained α-naphthol aralkyl cyanate ester compound was analyzed by infrared absorption spectroscopy, and －１ Absorption of cyanate ester groups was confirmed in the vicinity.

[0279] Synthesis Example 2: Synthesis of polymer (va) having structural units represented by formula (V) 2.25 moles (292.9 g) of divinylbenzene, 1.32 moles (172.0 g) of ethylvinylbenzene, 11.43 moles (1190.3 g) of styrene, and 15.0 moles (1532.0 g) of n-propyl acetate were charged into a reactor, and 600 mmol of a boron trifluoride diethyl ether complex was added at 70°C, followed by a reaction for 4 hours. The polymerization reaction was terminated with an aqueous sodium bicarbonate solution, and the oil layer was washed three times with pure water. The mixture was then subjected to reduced pressure devolatilization at 60°C, and polymer (va) having structural units represented by formula (V) was recovered. The obtained polymer (va) having structural units represented by formula (V) was weighed, and it was confirmed that 860.8 g of polymer (va) having structural units represented by formula (V) was obtained.

[0280] The resulting polymer (va) having a structural unit represented by formula (V) had a number average molecular weight Mn of 2,060, a weight average molecular weight Mw of 30,700, and a monodispersity Mw / Mn of 14.9. １３ C-NMR and １ By performing H-NMR analysis, resonance lines derived from each monomer unit used as a raw material were observed in polymer (va) having a structural unit represented by formula (V). Based on the NMR measurement results and GC analysis results, the proportion of each monomer unit (structural unit derived from each raw material) in polymer (va) having a structural unit represented by formula (V) was calculated as follows: structural units derived from divinylbenzene: 20.9 mol% (24.3 mass%), structural units derived from ethylvinylbenzene: 9.1 mol% (10.7 mass%), structural units derived from styrene: 70.0 mol% (65.0 mass%), and the proportion of structural units having a residual vinyl group derived from divinylbenzene was 16.7 mol% (18.5 mass%).

[0281] <Measurement of Weight-Average Molecular Weight and Number-Average Molecular Weight> The weight-average molecular weight and number-average molecular weight were measured by gel permeation chromatography (GPC) using a liquid pump (Shimadzu Corporation, LC-20AD), a differential refractive index detector (Shimadzu Corporation, RID-10A), 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, a column temperature of 40°C, and a calibration curve based on monodisperse polystyrene.

[0282] Example 1 <Production of copper foil-clad laminate (1-1)> A prepreg formed from an S-glass woven fabric (thickness 100 μm) and a resin composition (1-1) was produced according to Example 1 of WO 2020 / 022084. Specifically, it was produced as follows. First, 5.3 parts by mass of diallyl bisphenol A (DABPA, Daiwa Chemical Industry Co., Ltd.), 5.8 parts by mass of biscresol fluorene (BCF, Osaka Gas Chemical Co., Ltd.), 4.4 parts by mass of epoxy-modified silicone 1 (X-22-163, Shin-Etsu Chemical Co., Ltd., functional group equivalent 200 g / mol), 8.7 parts by mass of epoxy-modified silicone 2 (KF-105, Shin-Etsu Chemical Co., Ltd., functional group equivalent 490 g / mol), 5.8 parts by mass of biphenyl-type epoxy compound (YL-6121H, Mitsubishi Chemical Corporation), and 30 parts by mass of propylene glycol monomethyl ether acetate (DOWANOLPMA, Dow Chemical Japan Co., Ltd.) as a solvent were added to a three-neck flask equipped with a thermometer and a Dimroth trap, and the mixture was heated to 120°C in an oil bath with stirring. After confirming that the raw materials had dissolved in the solvent, 0.3 parts by mass of imidazole catalyst g1 (TBZ, Shikoku Chemical Industry Co., Ltd.) was added, the temperature was raised to 140°C, and the mixture was stirred for 5 hours. After cooling, a phenoxy polymer solution (solid content 50% by mass) was obtained (polymer production step).

[0283] To 30 parts by mass (solid content equivalent) of this phenoxy polymer solution, 26 parts by mass of the α-naphthol aralkyl cyanate ester compound (SNCN) (cyanate equivalent: 261 g / eq.) obtained in Synthesis Example 1, 17 parts by mass of a novolak maleimide compound (BMI-2300, Daiwa Chemical Industry Co., Ltd.), and 27 parts by mass of a naphthylene ether epoxy compound (HP-6000, DIC Corporation) were added. 100 parts by mass of spherical silica (SFP-130MC, Denka Co., Ltd.), 40 parts by mass of spherical silica (SC-4500SQ, Admatechs Co., Ltd.), 1 part by mass of a wetting and dispersing agent (DISPERBYK-161, BYK Japan Co., Ltd.), and 5 parts by mass of a silane coupling agent (KMB-403, Shin-Etsu Chemical Co., Ltd.) were mixed to obtain a varnish (resin composition (1-1)) (varnish production step). This varnish was impregnated and coated onto a glass cloth (S-glass woven fabric, thickness 100 μm), and heated and dried at 150 ° C. for 3 minutes to obtain a prepreg of an insulating resin layer (1-1) (solid content (including filler) 46% by mass) (prepreg production step).

[0284] Eight sheets of the prepreg obtained above were stacked, and electrolytic copper foil (3EC-M2S-VLP, manufactured by Mitsui Mining & Smelting Co., Ltd.) having a thickness of 12 μm was placed on top and bottom of the stack. Then, a pressure of 30 kgf / cm was applied. ２ The laminate was then subjected to lamination molding at a temperature of 220° C. for 120 minutes to obtain a copper foil-clad laminate (1-1) having an insulating resin layer (1-1) with a thickness of 0.8 mm formed from the resin composition (1-1).

[0285] <Measurement of Dielectric Loss Tangent (Df)> The copper foils on both sides of the copper foil-clad laminate (1-1) were removed by etching, and the laminate was dried at 120°C for 60 minutes. The dielectric loss tangent (Df) after drying was measured at 10 GHz using a perturbation cavity resonator. The measurement temperature was 23°C. The perturbation cavity resonator used was an Agilent 8722ES manufactured by Agilent Technologies. The relative dielectric constant (Dk) can also be measured in the same manner. Evaluation was performed in the following categories.

[0286] <<Dielectric loss tangent (Df)>> A: 0.005 or less B: More than 0.005 and less than 0.008 C: More than 0.008 and less than 0.011 D: More than 0.011

[0287] <Thermal expansion coefficient> The coefficient of thermal expansion (CTE: Coefficient of linear thermal expansion) was measured by the TMA method (Thermo-Mechanical Analysis) defined in JIS C 6481 5.19, and the coefficient of thermal expansion (CTE) was determined as follows. Specifically, the copper foil on both sides of the copper foil-clad laminate (1-1) obtained above was removed by etching, and the evaluation sample was cut (downsized) to 5.0 mm × 5.0 mm × 0.8 mm. Using a thermomechanical analyzer (TA Instruments, TMA Q-400), the temperature was increased from 30 ° C. to 320 ° C. at a rate of 10 ° C. per minute, and the thermal expansion coefficient (CTE (X-Y)) in the thickness direction from 50 ° C. to 280 ° C. (unit: ppm / ° C.) was measured. The ppm is a volume ratio. Other details are in accordance with the above JIS C 6481 5.19. Evaluation was carried out as follows. The ppm is a volume ratio. Other details are in accordance with the above JIS C 6481 5.19. Evaluation was carried out as follows. The evaluation results are shown in Table 1. A: 10 ppm / °C or less B: More than 10 ppm / °C and 15 ppm / °C or less C: More than 15 ppm / °C and 20 ppm / °C or less D: More than 20 ppm / °C

[0288] <Production of Copper Foil (2) with Insulating Resin Layer (2)> 5 parts by mass of a maleimide compound (MIR-3000, manufactured by Nippon Kayaku Co., Ltd., corresponding to the compound represented by formula (M3)), 29 parts by mass of a maleimide compound (ma) shown in the structure below (NE-X-9470S, manufactured by DIC Corporation, corresponding to the compound represented by formula (M1)), 30 parts by mass of the polymer (va) having a structural unit represented by formula (V) obtained in Synthesis Example 2, 15 parts by mass of a hydrogenated styrene-based thermoplastic elastomer (SEBS, block copolymer, SEPTON 2104, Mn 83000, manufactured by Kuraray Co., Ltd.), and the α-naphthol aralkyl cyanate ester compound (SNCN) (cyanate equivalent: 261 g / eq.) obtained in Synthesis Example 1. 5 parts by mass of phosphorus-based flame retardant (PX-200, Daihachi Chemical Industry Co., Ltd.) 15 parts by mass of N-phenylmaleimide (Tokyo Chemical Industry Co., Ltd., product number: P0900) 1 part by mass, wetting dispersant (BYK Corporation, BYK-2009) 0.3 parts by mass, wetting dispersant (DISPERBYK-161, BYK Japan Co., Ltd.) 0.5 parts by mass, methyl ethyl ketone (MEK) slurry of vinylsilane-treated silica (SC2050MNU (trade name), median diameter 0.5 μm, non-volatile content 70% by mass, Admatechs Co., Ltd.) 100 parts by mass were dissolved, dispersed and mixed in methyl ethyl ketone to obtain a varnish (resin composition (2)). Note that the above-mentioned amounts added indicate the solid content.

[0289] Maleimide compound (ma) n is an integer of 1 to 20. 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 copper foil (2) with an insulating resin layer (2) having a thickness of 20 μm. In the same manner as above, the dielectric loss tangent (Df) and thermal expansion coefficient of the cured product of the insulating resin layer (2) were measured. The evaluation categories were as follows:

[0290] <<Dielectric dissipation factor (Df)>> A: 0.005 or less B: More than 0.005 and less than 0.008 C: More than 0.008 and less than 0.011 D: More than 0.011 <<Coefficient of thermal expansion>> A: 10 ppm / °C or less B: More than 10 ppm / °C and less than 15 ppm / °C C: More than 15 ppm / °C and less than 20 ppm / °C D: More than 20 ppm / °C

[0291] <Production of a multilayer body> The copper foils on both sides of the copper foil-clad laminate (1-1) and one of the copper foils (2) with the insulating resin layer (2) are removed by etching, and the copper foils (2) with the insulating resin layer (2) are placed so that the insulating resin layer (2) faces each of the two insulating resin layers (1-1) of the copper foil-clad laminate (1-1), respectively, and a pressure of 30 kgf / cm is applied. ２ The laminate was then heat-pressed at 220° C. for 120 minutes to obtain a multilayer structure consisting of copper foil / insulating resin layer (2) / insulating resin layer (1-1) / insulating resin layer (2) / copper foil.

[0292] <Dielectric loss tangent (Df)> The linear expansion coefficient of the obtained multilayer body was measured by the same method as in <Measurement of dielectric loss tangent (Df)> above. Evaluation was performed as follows. The evaluation results are shown in Table 1.

[0293] <<Dielectric Dissipation Factor (Df)>> A: 0.005 or less B: More than 0.005 and 0.008 or less C: More than 0.008 and 0.011 or less D: More than 0.011 <Thermal Expansion Coefficient> The linear expansion coefficient of the obtained multilayer body was measured by the same method as in <Thermal Expansion Coefficient> above. Evaluation was performed as follows. The evaluation results are shown in Table 1. A: 10 ppm / °C or less B: More than 10 ppm / °C and 15 ppm / °C or less C: More than 15 ppm / °C and 20 ppm / °C or less D: More than 20 ppm / °C

[0294] <Skew Measurement> Only one side of the copper foil of the multilayer structure consisting of copper foil / insulating resin layer (2) / insulating resin layer (1-1) / insulating resin layer (2) / copper foil obtained above was etched to form 15 microstrip lines with a circuit length of 10 cm. The transmission speed of the 15 conductor wirings (impedance 50Ω) from 10 GHz to 40 GHz was measured, and the difference between the maximum and minimum values ​​was calculated as the skew. A: The difference between the maximum and minimum values ​​was 5.0 x 10 ー１２ s or less B: The difference between the maximum and minimum values ​​is 5.0 x 10 ー１２s super 10.0x10 ー１２ s or less C: The difference between the maximum and minimum values ​​is 10.0 x 10 ー１２ s super

[0295] <Measurement of Transmission Loss> Only one side of the copper foil of the multilayer structure consisting of copper foil / insulating resin layer (2) / insulating resin layer (1-1) / insulating resin layer (2) / copper foil obtained above was etched to form a microstrip line with a circuit length of 10 cm, to produce a wiring board, and the transmission characteristics were evaluated. A high-frequency signal was transmitted using a network analyzer N5227B manufactured by Keysight Technology, and the transmission loss at 40 GHz was measured. A: 0.7 dB / cm or less B: More than 0.7 dB / cm and 1.0 dB / cm or less C: More than 1.0 dB / cm

[0296] Example 2 The same procedure as in Example 1 was carried out, except that an insulating resin layer (1-2) was produced by replacing the prepreg used for the insulating resin layer (1-1) with the prepreg shown below. A mixture of 1 part by mass of alumina nanoparticles (product name "NANOBYK-3610", average particle size: 20 nm, manufactured by BYK Japan KK) surface-treated with a polysiloxane-based modifier, 300 parts by mass of spherical fused silica (product name "FB-3SDC", average particle size: 3.0 μm, manufactured by Denki Kagaku Kogyo Kabushiki Kaisha), 100 parts by mass of spherical fused silica (SFP-120MC, average particle size: 0.3 μm, manufactured by Denki Kagaku Kogyo Kabushiki Kaisha), 36 parts by mass of the α-naphthol aralkyl cyanate ester compound (SNCN) (cyanate equivalent: 261 g / eq.) obtained in Synthesis Example 1, and a maleimide compound (product name "BMI-2300 "), 26 parts by mass of a naphthylene ether type epoxy compound (product name "HP-6000", epoxy equivalent: 250 g / eq., manufactured by DIC Corporation), 38 parts by mass of a wetting dispersant (product name "disperbyk-161", manufactured by BYK Japan KK), 1 part by mass of a wetting dispersant (product name "disperbyk-111", manufactured by BYK Japan KK), 5 parts by mass of a silane coupling agent (product name "Z6040", manufactured by Toray Dow Coating Co., Ltd.), and 1 part by mass of 2,4,5-triphenylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed to obtain a varnish (resin composition (1-2)). This varnish was diluted with methyl ethyl ketone, impregnated and coated onto a 0.1 mm thick E-glass woven fabric, and dried by heating at 140°C for 3 minutes to obtain a prepreg of insulating resin layer (1-2) (solid content (including filler) 63% by mass).

[0297] Comparative Example 1 The copper foil-clad laminate (1-1) produced in Example 1 was measured for dielectric loss tangent (Df), coefficient of thermal expansion, skew, and transmission loss in the same manner as in the Examples.

[0298]

[0299] In Table 1 above, ΔDf represents Df of the first insulating resin layer - Df of the second insulating resin layer.

[0300] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.

[0301] REFERENCE SIGNS LIST 1 Multilayer body 2 First insulating resin layer 3 Second insulating resin layer 4 Metal foil 41 Metal foil 5 Metal wiring 6 Third insulating resin layer 7 First insulating resin layer with metal foil

Claims

1. A multilayer body having a first insulating resin layer and a second insulating resin layer in contact with the first insulating resin layer, wherein the dielectric loss tangent of the second insulating resin layer at a frequency of 10 GHz measured using a perturbation method cavity resonator is lower than the dielectric loss tangent of the first insulating resin layer at a frequency of 10 GHz measured using the perturbation method cavity resonator.

2. The multilayer body according to claim 1, wherein the first insulating resin layer has a thermal expansion coefficient of 30 ppm / °C or less as measured according to the TMA (thermo-mechanical analysis) method.

3. The multilayer body according to claim 1, wherein the difference between the dielectric loss tangent of the second insulating resin layer and the dielectric loss tangent of the first insulating resin layer is 0.002 or more.

4. The multilayer body according to claim 1, wherein the coefficient of thermal expansion of the first insulating resin layer measured in accordance with the TMA (Thermo-mechanical analysis) method is 30 ppm / °C or less, and the difference between the dielectric loss tangent of the second insulating resin layer and the dielectric loss tangent of the first insulating resin layer is 0.002 or more.

5. The multilayer body according to any one of claims 1 to 4, wherein the first insulating resin layer contains a fibrous base material.

6. A multilayer body according to any one of claims 1 to 4, wherein the first insulating resin layer is a layer formed from a resin composition (1) containing a thermosetting compound and a fiber substrate.

7. The multilayer body according to any one of claims 1 to 4, wherein the second insulating resin layer does not contain a fibrous base material.

8. The multilayer body according to claim 7, wherein the second insulating resin layer is a layer formed from a resin composition (2), the resin composition (2) contains a thermosetting compound, and the content of a filler is 0 to 40 mass % of the mass of the resin solid content contained in the resin composition (2).

9. The multilayer body according to any one of claims 1 to 4, wherein the second insulating resin layer is disposed so as to be in contact with both surfaces of the first insulating resin layer.

10. The multilayer body according to claim 9, further comprising a metal foil disposed in contact with the surface of the second insulating resin layer opposite to the first insulating resin layer.

11. The multilayer body according to any one of claims 1 to 4, further comprising a metal foil disposed in contact with the surface of the second insulating resin layer opposite to the first insulating resin layer.

12. The multilayer body according to claim 11, wherein the metal foil provided in contact with the surface of the second insulating resin layer has a surface roughness Rz of 0.2 to 4.0 μm as measured in accordance with JIS B0601:2013.

13. The multilayer body according to claim 1, wherein the coefficient of thermal expansion of the first insulating resin layer measured in accordance with the TMA (Thermo-mechanical analysis) method is 30 ppm / °C or less, the difference between the dielectric loss tangent of the second insulating resin layer and the dielectric loss tangent of the first insulating resin layer is 0.002 or more, the first insulating resin layer is a layer formed from a resin composition (1) containing a thermosetting compound and a fiber substrate, the second insulating resin layer does not contain a fiber substrate, the second insulating resin layer is a layer formed from a resin composition (2), the resin composition (2) contains a thermosetting compound and has a filler content of 0 to 40 mass% of the mass of the resin solid content contained in the resin composition (2), and the second insulating resin layer is arranged so as to be in contact with both surfaces of the first insulating resin layer.

14. The multilayer body according to claim 13, further comprising a metal foil disposed in contact with the surface of the second insulating resin layer opposite to the first insulating resin layer.

15. The multilayer body according to claim 13, further comprising metal wiring provided on the surface of said second insulating resin layer.

16. The multilayer body according to claim 14, further comprising a third insulating resin layer provided on the surface of said second insulating resin layer and covering said metal wiring.

17. The multilayer body according to claim 1, 2 or 13, which has an outer layer circuit and / or element provided on the surface of the second insulating resin layer.

18. The multilayer body according to any one of claims 1 to 4 and 13 to 16, wherein the first insulating resin layer is a layer formed from a resin composition (1) and a fiber substrate, and the resin composition (1) is in a cured state; the second insulating resin layer is a layer formed from a resin composition (2), and the resin composition (2) is in a cured state; the resin composition (1) contains a thermosetting compound; the resin composition (2) contains a thermosetting compound; and the content of a filler is 0 to 40 mass% of the mass of the resin solid content contained in the resin composition (2).

19. A method for producing a multilayer body according to any one of claims 1 to 4 and 13 to 16, comprising bonding the second insulating resin layer side of a second insulating resin layer having a metal foil on one surface to the first insulating resin layer.

20. A method for producing a multilayer body according to claim 19, comprising obtaining the second insulating resin layer having a metal foil on one surface by removing the protective film from a metal foil-covered second insulating resin layer having a metal foil on one surface and a protective film on the other surface.

21. The method for producing a multilayer body according to claim 19, comprising bonding the first insulating resin layer and the second insulating resin layer in a semi-cured state.

22. A printed wiring board comprising the multilayer body of any one of claims 1 to 4 and 13 to 16.

23. A semiconductor device comprising the printed wiring board according to claim 22.

24. A method for producing a printed wiring board, comprising the method for producing the multilayer body according to claim 20.

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